Omkar and Tree

#include<bits/stdc++.h>
using namespace std;
#define suni ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL)
int main()
{
    ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
    long long  n, m, u, a,b,c;
    map<long long, bool> mp;
    int tc;
    cin>>tc;
    while(tc--)
    {
        mp.clear();
        cin>>n>>m;
        for(long long i=1; i<=m; i++)
        {
            cin>>a>>b>>c;
            mp[b] = true;
        }
        for(long long i=1; i<=n; i++)
        {
            if(mp[i] == false)
            {
                u= i;
                break;
            }
        }
        for(long long i=1; i<=n; i++)
        {
            if(i != u) cout<<u<<" "<<i<<endl;
        }
    }
}