func_code_string: #include <bits/stdc++.h>   using namespace std;   int n, x, a, ans, r[2001], t[2001][2001];   bool f[2001][2001];   int main() {     scanf( %d , &n);     for (int _ = 1; _ <= n; _++)       while (scanf( %d: , &x)) {         r[_]++;         for (int i = 1; i < x; i++) scanf( %d, , &a), t[_][a] = x;         scanf( %d , &a), t[_][a] = x;         if (getchar() !=  - ) break;       }     for (int i = 1; i <= n; i++)       for (int j = i + 1; j <= n; j++)         if (t[i][j] + t[j][i] == n) f[i][j] = f[j][i] = true, ans++;     if (ans != (n - 1)) return printf( -1 n ), 0;     for (int i = 1; i <= n; i++) {       a = 0;       for (int j = 1; j <= n; j++)         if (f[i][j]) a++;       if (a != r[i]) return printf( -1 n ), 0;     }     printf( %d n , ans);     for (int i = 1; i <= n; i++)       for (int j = i + 1; j <= n; j++)         if (f[i][j]) printf( %d %d n , i, j);     return 0;   }   