(;
GM[1]
SZ[19]
AW[db][fc][hd][jd][mc][me][oe]
AB[cc][dd][df][cj][oc][qd][pf][ph]
LB[pf:2][oe:1]
C[Problem 99. White to play.  

After the exchange of White 1 for Black 2, Black's position looks very strong. However, there is a way for White to launch a successful invasion. ]
;W[qc]
TE[2]
C[Correct Answer.  

White 1 is a tesuji. ]
(;B[rc]
C[If Black blocks at 2, ... ]
;W[rd]
C[... White crosscuts with 3. Next, ... ]
(;B[qb]
C[... if Black 4, ... ]
;W[qe]
C[... White 5. <= ]
)
(;B[re]
C[... if Black 4, ... ]
;W[pd]
C[... White 5. White has succeeded. <= ]
))
(;B[pd]
C[Variation.  

If Black plays 2, ... ]
;W[pb];B[ob];W[rd];B[re];W[rb];B[sd];W[sc]
C[... White can live in the corner with a ko by playing the moves to 9. ]
;B[rc]
C[<= ]
)
)