func_code_string: #include <bits/stdc++.h>   using namespace std;   constexpr int maxn = 2e5 + 10, N = 260, M = 5e6 + 10;   constexpr int MAX_INF = 0x3f3f3f3f;   int mp[maxn];   int main() {     int T;     cin >> T;     while (T--) {       int n, m;       scanf( %d%d , &n, &m);       int root = 0;       memset(mp, 0, sizeof(mp));       while (m--) {         int a, b, c;         scanf( %d%d%d , &a, &b, &c);         mp[b] = 1;       }       for (int i = 1; i <= n; i++) {         if (!mp[i]) {           root = i;           break;         }       }       for (int i = 1; i <= n; i++) {         if (i == root) continue;         printf( %d %d n , i, root);       }     }   }   