func_code_string: #include <bits/stdc++.h>   using namespace std;   double pi = acos(-1);   struct point {     int x, y;   } p[2005];   vector<double> v;   int main() {     int n;     scanf( %d , &n);     for (int i = 1; i <= n; i++) scanf( %d%d , &p[i].x, &p[i].y);     long long ans = 0;     for (int i = 1; i <= n; i++) {       v.clear();       for (int j = 1; j <= n; j++)         if (j != i) v.push_back(atan2(p[j].y - p[i].y, p[j].x - p[i].x));       sort(v.begin(), v.end());       int k = 0;       int now = 0;       for (int j = 0; j < v.size(); j++) {         while (v[k] + now * pi < v[j] + pi) {           k++;           if (k >= v.size()) k = 0, now += 2;         }         int w = (j - k >= 0 ? j - k : k - j - 1);         ans += 1ll * w * (w - 1) / 2 * (n - w - 2) * (n - w - 3) / 2;       }     }     printf( %lld n , ans / 2);     return 0;   }   