func_code_string: #include <bits/stdc++.h>   using namespace std;   void solve();   void precalc();   int main() {     string s =  change me please ;     int t = 1;     while (t--) solve();     return 0;   }   void solve() {     int n;     cin >> n;     vector<int> a(n), h(n);     for (int i = 0; i < n; ++i) cin >> a[i] >> h[i];     int ans = 0;     for (int i = 0; i < n; ++i)       for (int j = 0; j < n; ++j)         if (a[i] == h[j]) ++ans;     cout << ans;   }   