func_code_string: #include <bits/stdc++.h>   int vi[60], ho[60];   int main() {     int n, k, i;     int x, y;     scanf( %d , &n);     for (k = 1; k <= n * n; k++) {       scanf( %d%d , &x, &y);       if (vi[x] || ho[y]) continue;       vi[x] = 1;       ho[y] = 1;       printf( %d  , k);     }   }   