(No. 204: Mar. 20, 2000)
Elementary level: Answer
Black 1 is the vital point. Black captures
the five White stones in an Oiotoshi.
Intermediate level: Answer
Black 1 is crucial to capture the five White stones.
If White 2 to 6, Black 7 captures the White.
Intermediate level: Wrong Answer
Black 1 is wrong. After White 2,
Black has no way to capture the White.