func_code_string: #include <bits/stdc++.h>   using namespace std;   int n, m, k;   bool debug = false;   int main() {     scanf( %d , &n);     int x, y;     long long sum = 0, ss = 0, px = 0, py = 0;     for (int i = 0; i < n; i++) {       scanf( %d%d , &x, &y);       sum += (long long)x * x + (long long)y * y;       ss += px * x + py * y;       px += (long long)x;       py += (long long)y;     }     sum = sum * (n - 1);     sum -= 2 * ss;     cout << sum << endl;     return 0;   }   