func_code_string: #include <bits/stdc++.h>   using namespace std;   int a[122], b[122];   int main() {     int n, k, t, ans = 0;     cin >> n;     for (int i = 0; i < n; i++) {       cin >> k >> t;       a[k]++;       b[t]++;     }     for (int i = 1; i <= 100; i++)       if (a[i] > 0) ans += a[i] * b[i];     cout << ans << endl;   }   