Cow curling is a popular cold-weather sport played in the Moolympics.
Like regular curling, the sport involves two teams, each of which slides N heavy stones (3 <= N <= 50,000) across a sheet of ice. At the end of the game, there are 2N stones on the ice, each located at a distinct 2D point.
Scoring in the cow version of curling is a bit curious, however. A stone is said to be "captured" if it is contained inside a triangle whose corners are stones owned by the opponent (a stone on the boundary of such a triangle also counts as being captured). The score for a team is the number of opponent stones that are captured.
Please help compute the final score of a cow curling match, given the locations of all 2N stones.
有两支队伍在比赛，一队可以一次取出3个点来，所围成的三角形覆盖的区域可以“捕获”对方的点，问两支队伍各能够捕获对方多少个点。