CF552D Vanya and Triangles

Vanya got bored and he painted $ n $ distinct points on the plane. After that he connected all the points pairwise and saw that as a result many triangles were formed with vertices in the painted points. He asks you to count the number of the formed triangles with the non-zero area.

The first line contains integer $ n $ ( $ 1

In the first line print an integer — the number of triangles with the non-zero area among the painted points.

Note to the first sample test. There are $ 3 $ triangles formed: $ (0,0)-(1,1)-(2,0) $ ; $ (0,0)-(2,2)-(2,0) $ ; $ (1,1)-(2,2)-(2,0) $ . Note to the second sample test. There is $ 1 $ triangle formed: $ (0,0)-(1,1)-(2,0) $ . Note to the third sample test. A single point doesn't form a single triangle.