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A mathematical problem of permutation and combination
When all right rowers are selected from three people who can only paddle right, there are 336 kinds of C (3,3) * C (8,3).

When one of the rowers is two cities: C (3,2) * C (4,1) * C (7,3) = 420.

There are two kinds of cities rowing right oars: C(3,1) * c (4,2) * c (6,3) = 360.

When all right oars are two kinds of cities: c (4,3) * c (5,3) = 40 kinds.

* * * 336+420+360+40 =1156 species.