func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     int n;     scanf( %d , &n);     vector<long long> X(n + 1), Y(n + 1);     for (int i = (1); i <= (n); ++i) scanf( %lld%lld , &X[i], &Y[i]);     long long S = 0;     for (int k = (1); k <= (n); ++k) {       vector<double> V;       for (int i = (1); i <= (n); ++i)         if (i != k) V.push_back(atan2(Y[i] - Y[k], X[i] - X[k]));       sort(V.begin(), V.end());       V.insert(V.end(), V.begin(), V.end());       for (int i = 0, j = 0; i + 1 < n; i++) {         while (V[j] + (j >= n - 1 ? 2 * acos(-1) : 0.0) - V[i] < acos(-1)) j++;         long long x = j - 1 - i, y = n - 2 - x;         S += x * (x - 1) / 2 * y * (y - 1) / 2;       }     }     printf( %lld n , S / 2);     return 0;   }   