func_code_string: #include <bits/stdc++.h>   using namespace std;   const int maxn = 5e3 + 5;   const int N = 1e4 + 5;   const int inf = 0x3f3f3f3f;   struct hor {     int x1, x2, y;     bool operator<(const hor& a) const { return y < a.y; }   } h[maxn];   struct ver {     int y1, y2, x;     bool operator<(const ver& a) const { return y1 < a.y1; }   } v[maxn];   int n, cntv, cnth;   int c[N];   int lowbit(int x) { return x & (-x); }   int sum(int x) {     int ans = 0;     for (int i = x; i > 0; i -= lowbit(i)) ans += c[i];     return ans;   }   int get_sum(int l, int r) { return sum(r) - sum(l - 1); }   void update(int x, int val) {     for (int i = x; i <= N; i += lowbit(i)) c[i] += val;   }   int main() {     scanf( %d , &n);     cntv = cnth = 0;     for (int i = 1; i <= n; ++i) {       int x1, y1, x2, y2;       scanf( %d %d %d %d , &x1, &y1, &x2, &y2);       x1 += 5001, y1 += 5001, x2 += 5001, y2 += 5001;       if (x1 == x2)         v[++cntv] = {min(y1, y2), max(y1, y2), x1};       else         h[++cnth] = {min(x1, x2), max(x1, x2), y1};     }     sort(h + 1, h + cnth + 1);     sort(v + 1, v + cntv + 1);     long long ans = 0;     for (int i = 1; i <= cnth; ++i) {       memset(c, 0, sizeof(c));       for (int j = 1, k = 1; k < i;) {         if (v[j].y1 <= h[k].y && j <= cntv) {           if (v[j].x >= h[i].x1 && v[j].x <= h[i].x2 && v[j].y2 >= h[i].y)             update(v[j].x, 1);           ++j;         } else {           int res = get_sum(h[k].x1, h[k].x2);           ans += 1ll * res * (res - 1) / 2;           ++k;         }       }     }     printf( %lld n , ans);     return 0;   }   