156 Combinatorial & Topological Problems
416. SINKING THE FISHING-BOATS
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tJ ~ ~ i) ~ <!l ~~ ~ ~ ~ ~ ~ ~~ 6 tJ lJ 6 tJ ~tJ l7 tJ b ~ & &There are forty-nine fishing-boats in the North Sea. How could an enemy
ram and sink the lot in twelve straight courses, starting from the place shown
and finishing up at the same place?
417. GOING TO CHURCH
A man living in the house shown in the diagram wants to know what is the
greatest number of different routes by which he can go to the church. The