func_code_string: #include <bits/stdc++.h>   using namespace std;   const int inf = (int)1e9;   const int mod = inf + 7;   const double eps = 1e-9;   int a[100][100];   int n, x, y;   bool u[400], u1[400];   vector<int> v;   int main() {     ios_base ::sync_with_stdio(false);     cin.tie(NULL);     cin >> n;     for (int i = 1; i <= n * n; i++) {       cin >> x >> y;       if (!u[x] && !u1[y]) {         u[x] = 1;         u1[y] = 1;         v.push_back(i);       }     }     for (int i = 0; i < v.size(); i++) {       cout << v[i] <<    ;     }     return 0;   }   