func_code_string: #include <bits/stdc++.h>   using namespace std;   int n, c, d;   const int maxn = 3456789;   const long double PI = acos((long double)(-1.0));   const long double eps = 1e-18;   long double ang[maxn];   int main() {     while (cin >> n >> c >> d) {       for (int i = 0; i < (n); i++) {         int r, w;         scanf( %d%d , &r, &w);         long double x = r - c;         long double y = w - d;         ang[i] = atan2(y, x);       }       sort(ang, ang + n);       for (int i = 0; i < (n + 3); i++) ang[i + n] = ang[i] + 2 * PI;       long long ans = 1LL * n * (n - 1) * (n - 2) / 6;       int j = 0, lo = 0, hi = 0;       for (int i = 0; i < (n); i++) {         while (ang[j + 1] - ang[i] < PI + eps) ++j;         while (ang[lo] - ang[i] < PI - eps) ++lo;         while (ang[hi + 1] - ang[i] < PI + eps) ++hi;         ans -= 1LL * (j - i) * (j - i - 1) / 2;         ans += 1LL * (hi - lo) * (hi - lo + 1) / 2;       }       cout << ans << endl;     }     return 0;   }   