7/18/2019 esercizi strategia
1/15
ChessBase 12 Stampa, Puricelli, 18/05/2015 1
exercise 001
a b c d e f g h
a b c d e f g h
8
7
6
5
4
2
1
8
7
6
5
4
2
1
.Exercises 1-20: The bishop.Black to play.Indicate your 1st move + short plan..
(press F10 for the solution)
Nikolic,StIvkov,B
(Diagramma)
1...Ae8! Heading for g6 to seize theb1-h7 diagonal . 2.Ag4 Db6+ 3.Rh1Ag6 4.Db1 Dc6 5.Db5 Dc8 6.Ta2Ae4 . The bishop is installed on ap r o t e c t e d s q u a r e . B l a c k h a s n oproblems..(press F10 for the next exercise)
a b c d e f g h
a b c d e f g h
8
7
6
5
4
2
1
8
7
6
5
4
2
1
exercise 002
a b c d e f g h
a b c d e f g h
8
7
6
5
4
2
1
8
7
6
5
4
2
1
.White to play.Indicate your 1st move + short plan..(press F10 for the solution)
7/18/2019 esercizi strategia
2/15
ChessBase 12 Stampa, Puricelli, 18/05/2015 2
Timman,JIkonnikov,V
a b c d e f g h
a b c d e f g h
8
7
6
5
4
2
1
8
7
6
5
4
2
1
1.c4! Clearing the long diagonal for theb i s hop , whe r e t he r e i s no b l ac kcounterpart . Cc7 2.Dc2 De7 3.Ae4!In order to soften up Black's kingside.
h6 4.Ab2 Ce8 5.Cc1! Heading for b3to harass the a5-bishop. Dd7 6.Ah7+
Rh8 7.Af5 Dc7 8.Cb3 . White has aclear advantage..(press F10 for the next exercise)
exercise 003
(Diagramma)
.Black to play.Indicate your 1st move + short plan..(press F10 for the solution)
a b c d e f g h
a b c d e f g h
8
7
6
5
4
2
1
8
7
6
5
4
2
1
Scholl,ETimman,J
a b c d e f g h
a b c d e f g h
8
7
6
5
4
2
1
8
7
6
5
4
2
1
1...Af8! Black prepares 2...Bh6 toimprove the passive bishop. 2.c3!
[ The game continued 2.Cc1? Ah63.Cd3 Dc3 4.Tde2 Ad2! and Whiteresigned. ]
2...Ah6
[ After 2...bxc3 3.Tc2 , followed byRxc3, White has fewer problems. ]
3.Tc2 a4![ Intending 3...a4 4.bxa4 Ta8
7/18/2019 esercizi strategia
3/15
ChessBase 12 Stampa, Puricelli, 18/05/2015
. Black keeps the initiative.
.(press F10 for the next exercise) ]
exercise 004
a b c d e f g h
a b c d e f g h
8
7
6
5
4
2
1
8
7
6
5
4
2
1
.White to play.Indicate your 1st move + short plan..(press F10 for the solution)
Hellsten,JFlores Rios,M
(Diagramma)
1.Df2! Preparing 2 Bd4 in order toseize the long diagonal.
[ A l s o i n t e r e s t i n g i s 1.Da3!?, attacking the d6-pawn. ]
1...Cc3 2.Cb2![ The immediate 2.Ad4?? failed to
Dxd4! 3.Dxd4 Ce2+ ][ while 2.Ab3?! Ab5 isn't convincingeither. ]
2...Ca4?!
a b c d e f g h
a b c d e f g h
8
7
6
5
4
2
1
8
7
6
5
4
2
1
[ Preferable was 2...Cb5 3.Ca4 Ca34.Cb6 Cxc4 5.Cxc4 Txc4! 6.Txc4Ab5 , reducing the material. ]
3.Ad4 Df8 4.Cd3! Planning to attackon the kingside.Tc7 5.Ab3 Tac8
6.Txc7 Txc7 7.e5! . White has a clearinitiative..(press F10 for the next exercise)
exercise 005
(Diagramma)
.
White to play.Indicate your 1st move + short plan..(press F10 for the solution)
7/18/2019 esercizi strategia
4/15
ChessBase 12 Stampa, Puricelli, 18/05/2015 4
a b c d e f g h
a b c d e f g h
8
7
6
5
4
2
1
8
7
6
5
4
2
1
Hellsten,JSahl,B
a b c d e f g h
a b c d e f g h
8
7
6
5
4
2
1
8
7
6
5
4
2
1
1.a3! With the strong plan of b3 b4 andBb3(+) to seize the a2 g8 diagonal.g6This leads to new weaknesses;
[ but after 1...Dd7 2.Df3!? , followedb y 3 b 4 , B l a c k i s a l s o u n d e rpressure. ]
2.Df3 h5 3.b4 Ab6 4.Ab3+ Rg75.De2! Cd7 6.Dc4 Not bad;
[ but 6.Dd2! was even stronger. ]6...Df8
[ Or 6...De8 7.De6! Dxe6 8.Axe6, and 9 Bc8. ]
7.De6 Cb8 8.g3 Rh7 9.Rg2Enabling a future f2 f4, whereas Black
is completely tied up.[ There followed 9.Rg2 Ca6 10.Dd7+Dg7 11.Dc8 axb4 12.axb4 Aa713.Ac4 Cb8 14.Ae6 Ca6 15.Ag8+!Dxg8 16.Dxb7+ Dg7 17.Dxa6with a quick win..(press F10 for the next exercise) ]
exercise 006
a b c d e f g h
a b c d e f g h
8
7
6
5
4
2
1
8
7
6
5
4
2
1
.
Black to play.Indicate your 1st move + short plan..(press F10 for the solution)
Oll,LGelfand,B
1...f5! Softening up the h1-a8 diagonalfor the bishop.
[ Obviously 1...d5? 2.e5is less constructive. ]
7/18/2019 esercizi strategia
5/15
ChessBase 12 Stampa, Puricelli, 18/05/2015 5
a b c d e f g h
a b c d e f g h
8
7
6
5
4
2
1
8
7
6
5
4
2
1
2.Ae3 Dd7 3.Cd4 Af6[ A l s o i n t e r e s t i n g i s 3...Cf6!?, stepping up the pressure on e4; forexample, 4.Dc2 Rh8 5.Db3?! fxe4!
6.Cxe6 exd3 7.Cxf8 Dh3! 8.Cd5Dg4! 9.h3 Df5 and Black wins Gelfand. ]
4.Cde2 Tae8 5.Tad1 g6 6.Ad4 e5[ Even stronger was 6...Cxf4! 7.Dxf4( or 7.Axf6 Cxe2 ) 7...e5 8.Axe5dxe5 with a clear edge. ]
7.Ae3 Ag7 8.fxe5 dxe5 9.Ah6[ At this point the simplest was 9.Ah6Td8! , attacking the d3-pawn, with aclear advantage after 10.Ag5 Tc8
Gelfand..
(press F10 for the next exercise) ]
exercise 007
(Diagramma)
.
Black to play.Indicate your 1st move + short plan..(press F10 for the solution)
a b c d e f g h
a b c d e f g h
8
7
6
5
4
2
1
8
7
6
5
4
2
1
Petrosian,TVSmyslov,V
a b c d e f g h
a b c d e f g h
8
7
6
5
4
2
1
8
7
6
5
4
2
1
1...d5! Sacrificing a pawn to clear thea1-h8 diagonal for the bishop. 2.Cxd5
[ Preferable was 2.exd5 e4 3.Cxe4Axb2 4.Af3 Axa3 5.Td3 Smyslov,al though Black's bishop pair andoutside passed pawn should tell in
the end. ]2...Axd5 3.exd5 Txc2 4.b3 e4!The passed pawn manages to advanceall the way to e3.5.g4 e3 6.Tg2 Td2!
7/18/2019 esercizi strategia
6/15
ChessBase 12 Stampa, Puricelli, 18/05/2015 6
7.Txd2 exd2 8.Ad1 Txd5 . With aclear advantage..(press F10 for the next exercise)
exercise 008
a b c d e f g h
a b c d e f g h
8
7
6
5
4
2
1
8
7
6
5
4
2
1
.White to play.Indicate your 1st move + short plan..(press F10 for the solution)
Brynell,SErnst,T
(Diagramma)
1.Cd3! Swapping off the knight on e5 inorder to clear the long diagonal towardsthe black king.Cxd3 2.Dxd3 b4Prevent ing 3 Qc3 and creat ing thethreat of 3...c4, which White parries
wi th h is next move.3.Tac1 Db64.De3! Heading for h6,
[ and preparing to meet 4.De3 c4 by5.Ad4! . ]
a b c d e f g h
a b c d e f g h
8
7
6
5
4
2
1
8
7
6
5
4
2
1
4...Te8 5.Tc2 Cb7?[ The last chance was 5...e5 , when6.dxe6 Txe6 7.Dc1 , intending Bd5,leaves White clearly better. ]
6.Dh6 Cd8 7.Tce2 Preparing Be4 andBxg6, a plan impossible to stop. Dc7
[ If 7...Af5 , then 8.g4 Ad3 9.Te3 c410.bxc4 Axc4 11.Ae4! e5 12.dxe6Cxe6 13.Axg6! and wins. ]
8.Ae4! e5[ Or 8...Af5 9.Axf5 gxf5 10.Te6!, heading for g6. ]
9.dxe6 Cxe6 10.Axg6! Ac8 11.Axf7+Dxf7 12.Te4 Cc7 13.Txe8+. In view of the imminent mate, Blackresigned..
(press F10 for the next exercise)
exercise 009
(Diagramma)
.
Black to play.Indicate your 1st move + short plan..(press F10 for the solution)
7/18/2019 esercizi strategia
7/15
ChessBase 12 Stampa, Puricelli, 18/05/2015 7
a b c d e f g h
a b c d e f g h
8
7
6
5
4
2
1
8
7
6
5
4
2
1
Janowski,DCapablanca,JR
a b c d e f g h
a b c d e f g h
8
7
6
5
4
2
1
8
7
6
5
4
2
1
1...b4! Sacrificing a pawn in order toenter with the bishop on a4 and c2.
[ Another sensib le idea i s 1...Rf8!?, preparing ...Be8-h5. ]
2.axb4[ Or 2.Axb4 Aa4! (avoiding 2...Axb4
3.axb4 Aa4 4.Ta1 ) 3.Axe7 Rxe74.Tbc1 Tb8 with strong pressure. ]
2...Aa4 3.Ta1[ On 3.Tc1 Black might consider
Txf4+!? 4.Rxf4 Ag5+ , recoveringthe material with a superior position. ]
3...Ac2 4.Ag3 Ae4+ 5.Rf2 h5! 6.Ta7The only way to parry the threat of 6...
h4. Axg2 7.Txg2 h4 8.Axh4 Txg2+9.Rf3 Txh2 10.Axe7 Th3+ 11.Rf2Tb3 . Black soon won..(press F10 for the next exercise)
exercise 010
a b c d e f g h
a b c d e f g h
8
7
6
5
4
2
1
8
7
6
5
4
2
1
.White to play.Indicate your 1st move + short plan..
(press F10 for the solution)
Bjarnason,SHellsten,J
(Diagramma)
1.a4! White prepares 2 Ba3 to activatethe bishop. Cc7?!
[ 1...Axd5 2.axb5 Ae6 3.Aa3 Te8was preferable, although White is
7/18/2019 esercizi strategia
8/15
ChessBase 12 Stampa, Puricelli, 18/05/2015 8
a b c d e f g h
a b c d e f g h
8
7
6
5
4
2
1
8
7
6
5
4
2
1
better anyway thanks to his strongbishop pair. ]
2.Aa3 Txb1 3.Txb1 Te8 4.Ce3!Now the knight becomes awkward onc7. Ca8 5.Tb5 Dc7 6.Cd5 Axd5
7.exd5 . Intending d5-d6 with acrushing advantage..(press F10 for the next exercise)
exercise 011
(Diagramma)
.
Black to play.Indicate your 1st move + short plan..(press F10 for the solution)
a b c d e f g h
a b c d e f g h
8
7
6
5
4
2
1
8
7
6
5
4
2
1
Neishtadt,YKotov,A
a b c d e f g h
a b c d e f g h
8
7
6
5
4
2
1
8
7
6
5
4
2
1
1...d5! To clear the long diagonal forthe bishop. 2.exd5?!
[ Preferable was 2.Ac5! dxe4 3.De2with unclear play. ]
2...e4 3.De2 Cexd5 4.Cd1[ On 4.Ra1? t he re f ol lo ws Cxc3
5.Txc3 Cd5 and Black wins. ]4...Cd7 . With ideas like ...Ne5-d3 and.. .N7b6-a4, Black enjoys excel lentattacking prospects.
7/18/2019 esercizi strategia
9/15
ChessBase 12 Stampa, Puricelli, 18/05/2015 !
.(press F10 for the next exercise)
exercise 012
a b c d e f g h
a b c d e f g h
8
7
6
5
4
2
1
8
7
6
5
4
2
1
.White to play.Indicate your 1st move + short plan..(press F10 for the solution)
Beliavsky,ARomanishin,O
(Diagramma)
1.Af1! The bishop is transferred to thelong d iagonal where i t w i l l a t tackBlack's queenside.
[ 1.Ae2!? followed by Bf3 is similar ][ whereas 1.Ab2 Tac8 2.Tac1 Thd8is less incisive. ]
1...Tac8 2.Ag2 Ab4
[ Both 2...Axe3?! 3.fxe3 Txc34.Axb7 ][ and 2...Tc7 3.Ca4 Ab4 4.Td4!, i nt en di ng Ad6? 5.Txd6! Rxd6
a b c d e f g h
a b c d e f g h
8
7
6
5
4
2
1
8
7
6
5
4
2
1
6.Aa3+ , favour White. ]3.Ce2 Tc7 4.Rf1 Thc8 5.Ab2 b5?!Removing the pawn from the bishop'ss i g h t , b u t n o w t h e q u e e n s i d e i sweakened. 6.a4! bxa4 7.Txa4 a5
8.Aa3! Fighting for the a5-pawn.Axa39.Txa3 Cc5 10.Cd4 Cce4 11.Txa5. White later converted his extra pawninto victory..(press F10 for the next exercise)
exercise 013
(Diagramma)
.Black to play.Indicate your 1st move + short plan..(press F10 for the solution)
7/18/2019 esercizi strategia
10/15
ChessBase 12 Stampa, Puricelli, 18/05/2015 10
a b c d e f g h
a b c d e f g h
8
7
6
5
4
2
1
8
7
6
5
4
2
1
Brynell,SHellsten,J
a b c d e f g h
a b c d e f g h
8
7
6
5
4
2
1
8
7
6
5
4
2
1
1...f4! Sacrificing a pawn to enter withthe bishop along the b1-h7 diagonal.
[ After 1...Tc7 2.Cd3 Tc3 3.Cb4Db6 4.Tb1 , followed by 5 Bd2,White has more chances of survival. ]
2.Axf4 Af5! 3.e6+
[ Or 3.Te1 Ae4 , intending 4...g5, aswell as ...Qe6-g4. ]
3...Ra8 4.exf7 Ae4 5.Te1[ After 5.Rg1 Thf8! 6.Th2 Cc6
7.Ce5 g5 Black also enjoys a stronginitiative. ]
5...g5 6.hxg5 hxg5 7.Txe4 dxe4[ The immediate 7...Dh6!? was strong
as well. ]8.Cxg5 Dh6 9.Cxe4 Dh3+ 10.Rf3Dh5+ 11.g4 Dxf7 . Thanks to theexposed enemy king Black is clearlybetter..(press F10 for the next exercise)
exercise 014
a b c d e f g h
a b c d e f g h
8
7
6
5
4
2
1
8
7
6
5
4
2
1
.White to play.
Indicate your 1st move + short plan..(press F10 for the solution)
Giorgadze,GLerner,K
1.Ad2! White prepares Be1-g3 in order
to improve the bishop and reinforce thekingside defence. Rb8
[ After 1...h5 2.Ae1 h4 (or 2...hxg43.Ag3! Dg7 4.fxg4 , followed by
7/18/2019 esercizi strategia
11/15
ChessBase 12 Stampa, Puricelli, 18/05/2015 11
a b c d e f g h
a b c d e f g h
8
7
6
5
4
2
1
8
7
6
5
4
2
1
Raf2) 3.Tg2 , intending f3-f4, Whitei s c l e a r l y b e t t e r G i o r g a d z e .Obviously c losing the kingside isagainst Black's wishes. ]
2.Ae1 Ra8 3.Ab5!? Increasing thep r e s s u r e t o w a r d s t h e e n e m yqueenside.
[ Instead, the game continued 3.Tb2c4 4.Ac2 h5 5.Aa4 hxg4 6.Ag3Dc8 with unclear play ][ t h o u g h t h e s i m p l e 3.Ag3!?also deserves attention. ]
3...Db6 4.a4 a6 5.Ag3![ Now that 5.Ag3 axb5? 6.axb5+Ca7 fails to 7.Da4 , followed by Rfa1,White has seized the initiative..
(press F10 for the next exercise) ]
exercise 015
(Diagramma)
.
Black to play.Indicate your 1st move + short plan..(press F10 for the solution)
a b c d e f g h
a b c d e f g h
8
7
6
5
4
2
1
8
7
6
5
4
2
1
Sigurjonsson,GStein,L
a b c d e f g h
a b c d e f g h
8
7
6
5
4
2
1
8
7
6
5
4
2
1
1...d5! With the mission of clearing thelong diagonal for the bishop.2.e5 d4!Of course. Any other move permits 2Bd4 virtually burying the bishop on b7.
3.Cxd4[ Both 3.exf6 Axf6 ]
[ and 3.Axd4 Axf3 4.exf6 Axf6let Black recover the material with aclear edge. ]
3...Cg4 4.Ag1 Cxh2! 5.Tfc1
7/18/2019 esercizi strategia
12/15
ChessBase 12 Stampa, Puricelli, 18/05/2015 12
[ If 5.Axh2 , then Dxd4 ][ while 5.Rxh2 permits Axb4!, threatening mate on h4. ]
5...Cg4 6.Ce4 Axb4! 7.Cg5
White has to prevent the mate.Dd5!8.Cgf3 Dxb3 9.Cxb3 Ad5 . With asound extra pawn, Black is winning..(press F10 for the next exercise)
exercise 016
a b c d e f g h
a b c d e f g h
8
7
6
5
4
2
1
8
7
6
5
4
2
1
.White to play.Indicate your 1st move + short plan..
(press F10 for the solution)
Stein,LPetrosian,TV
(Diagramma)
1.a4! Sacrificing a pawn to seize the a3-f8 diagonal with the bishop.
[ O t h e r m o v e s , s u c h a s 1.Ta1?, permit the restrictive Aa4! . ]
a b c d e f g h
a b c d e f g h
8
7
6
5
4
2
1
8
7
6
5
4
2
1
1...Axa4[ Or 1...0-0 2.Ta1 Dd8 3.Aa3 Te84.Ad6 with a clear plus. ]
2.Ta1 b5 3.Aa3 Dd7 4.Tf2! Tb75.Taf1 Dd8 Black has managed tocover the f7-pawn, but White finds away to step up the pressure.6.Dd1!With ideas like Bh5, Qb1-b4 and Bxe6followed by Qg4.Th6 7.Ac1! Th7
8.Axe6![ In view of the decisive 8.Axe6 fxe69.Dg4 , Black resigned..(press F10 for the next exercise) ]
exercise 017
(Diagramma)
.Black to play.Indicate your 1st move + short plan..(press F10 for the solution)
7/18/2019 esercizi strategia
13/15
ChessBase 12 Stampa, Puricelli, 18/05/2015 1
a b c d e f g h
a b c d e f g h
8
7
6
5
4
2
1
8
7
6
5
4
2
1
Vilner,YRomanovsky,P
a b c d e f g h
a b c d e f g h
8
7
6
5
4
2
1
8
7
6
5
4
2
1
1...Te6! Preparing the strongmanoeuvre ...Bf8-c5-d4.2.Td3 Af8
3.Thd1[ After 3.De3 Ae7 4.Thd1 Df8!, a n d . . . B c 5 - d 4 , B l a c k a l s oaccomplishes his plan. ]
3...Ac5 4.De2 Ad4 5.Rb1 c5. Thanks to his tremendous bishopBlack is clearly better. Romanovskylater opened a new front by ...f7-f6.
.(press F10 for the next exercise)
exercise 018
a b c d e f g h
a b c d e f g h
8
7
6
5
4
2
1
8
7
6
5
4
2
1
.White to play.Indicate your 1st move + short plan..(press F10 for the solution)
Salov,VGurevich,M
(Diagramma)
1.b4! Preparing b4-b5 to soften up thelong diagonal for the bishop on g2.
Axc4?![ 1...Ce4 was preferable, althoughafter 2.Cxe4 fxe4 3.Cxe6 Dxe6
4.Dc2 Tfe8 5.Ae3 Cc7 6.Tfd1White is better thanks to his bishop
pair. ]2.b5 cxb5 3.Cdxb5
[ After 3.Axb7 b4! Black gets somecounterplay. ]
7/18/2019 esercizi strategia
14/15
ChessBase 12 Stampa, Puricelli, 18/05/2015 14
a b c d e f g h
a b c d e f g h
8
7
6
5
4
2
1
8
7
6
5
4
2
1
3...Td8 4.Aa3 One more piece intoplay.
[ 4.Cxd6 De6 5.Aa3 Ce8!is less clear. ]
4...d5 5.Cd6! Again White prefersactivity over material.De5 6.Cxc4
dxc4 7.Dc2 Cc5 8.--[ Now the game cont inued 8.Axc5?Dxc5 9.Tb5 Dd6 and White lost asignificant part of his advantage. ]
[ Much stronger was 8.Ca4! ; e.g. b69.Cxc5 bxc5 10.Dxc4+ with a hugeadvantage Salov..(press F10 for the next exercise) ]
exercise 019
(Diagramma)
.Black to play.Indicate your first 2 moves + short plan..
(press F10 for the solution)
a b c d e f g h
a b c d e f g h
8
7
6
5
4
2
1
8
7
6
5
4
2
1
Carlsen,MBeliavsky,A
a b c d e f g h
a b c d e f g h
8
7
6
5
4
2
1
8
7
6
5
4
2
1
1...Axd5! 2.Axd5[ After 2.exd5 e4! the bishop on g7w a k e s u p a n d a p a s s e d p a w nappears on the e-file. ]
2...Af6! Intending ...Bd8, ...c7-c6 and ...Bb6(+) in order to activate the bishop.
3.Dg3[ Or 3.Ag5 Dd8! 4.Axf6+ Txf6 5.Dg3c6 , when the g1-a7 diagonalbecomes useful for the queen. ]
7/18/2019 esercizi strategia
15/15
ChessBase 12 Stampa, Puricelli, 18/05/2015 15
3...c6 4.Ab3 Ad8! 5.Dd3[ Obvi ous ly the rest r ict ive 5.Ae3?failed to Cxe4 . ]
5...Ab6+ 6.Rh1
[ 6.Ae3 straight away waspreferable. ]6...Dg4! 7.Ae3
[ If 7.Dxd6 , then Tf2 8.Tg1 Dxg2+!with mate. ]
7...Axe3 8.Dxe3 Tf4 . With the doubleidea of 9...Nxe4 and 9...Ref8. Black isclearly better Beliavsky..(press F10 for the next exercise)
exercise 020
a b c d e f g h
a b c d e f g h
8
7
6
5
4
2
1
8
7
6
5
4
2
1
.White to play.Indicate your 1st move + short plan..(press F10 for the solution)
Beliavsky,A
Lautier,J
1.Af1! Redirecting the passive bishopto the h3-c8 diagonal where i t wi l l
a b c d e f g h
a b c d e f g h
8
7
6
5
4
2
1
8
7
6
5
4
2
1
complicate Black's long castling.[ 1.Axf6?! gxf6 2.Af1 is less exactdue to Cd4! , intending 3.Ah3 f5 . ]
1...Cd4[ On 1...Cxg3? there follows 2.Th8+Af8 3.Ah3 Dd6 4.De1! Cgh5 5.f4, destroying the black defence ]
[ while after 1...0-0-0?! 2.Axf6 gxf63.Ah3 Th8 4.Dd1! Rd8 5.Ag4the pin will soon take its toll. ]
2.f4![ The game saw 2.Th8+?! Af8 3.Ah3Dd6 4.f4 Cxd5 and Black eventuallysaved a draw. ]
2...Cf3[ After 2...Td8 3.De3 Cf5 4.Dd3!, intending 5 Ne4, White also enjoys
a strong initiative. ]3.De2 Cxg5 4.fxg5 Cg8 5.Th8 Rf8
[ Not 5...0-0-0? 6.Ah3 and wins. ]6.Ah3! De7 7.Ce4! . Intending Qh5-h7,as well as 8 Qg4! followed by 9 Nf6.White has an overwhelming initiative..(press F10 for the next exercise)