Fragmentation
Easy
Execution time limit is 1 second
Runtime memory usage limit is 64 megabytes
Determine the number of regions into which the diagonals of a convex polygon divide it, given that no three diagonals intersect at a single point.
Input
The first line contains a single integer N (3 ≤ N ≤ 50000) — the number of vertices of the polygon.
Output
Output a single integer — the number of regions formed.
Examples
Input #1
Answer #1
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