// UUID: 17070cba-117d-4cb6-a0a8-25b8000e8112
#include <bits/stdc++.h>
using namespace std;
#define int long long

template<class t>
std::ostream& operator<<(std::ostream& os, std::vector<t>v){
    for(t a : v){
        os << a<< " ";
    }
    os << "\n";
    return os;
}

void solve(){
    int n,m;
    cin >> n >> m;
    vector<vector<int>>adj(n);
    for(int i = 0; i < m; i++){
        int a,b;
        cin >> a >> b;
        adj[max(a,b)-1].push_back(min(a,b)-1);
    }
    //cout << adj;
    int rakt = 0;
    vector<bool>israkt(n);
    for(int i = 1; i < n; i++){
        int rcnt = 0;
        for(int v : adj[i]){
            if(israkt[v]){
                rcnt++;
            }
        }
        if(rcnt*2 < adj[i].size()){
            rakt++;
            israkt[i]= true;
        }
    }
    cout << rakt << endl;
    for(int i = 0; i < n; i++){
        if(israkt[i]){
            cout << i+1 << ' ';
        }
    }
    cout << endl;
}

signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    int t;
    cin >> t;
    while(t--){
        solve();
    }
}