(No. 149: Mar. 1, 1999)
Black 1 is crucial to live. If White 2,
Black plays 3 to capture the two White stones.

Elementary level: Variation
If White 2, Black plays 3 and 5 to capture
the White stones in an Oiotoshi.

Elementary level: Wrong Answer 1
Black 1 is wrong. After White 2, Black is dead.

Elementary level: Wrong Answer 2
Black 1 also fails. After White 2,
Black gets no more than a Ko with 3 and 5.

The combination of Black's moves 1 and 3 is crucial
to kill White. After Black 9, White is dead.

Intermediate level: Wrong Answer 1
Black 1 allows White to live with 2.
(The same shape as the elementary problem No.148.)

Intermediate level: Wrong Answer 2
Black 1 allows White to live with 2.
