#include <bits/stdc++.h>
#include<iostream>
#include<map>
#include<vector>
#include <algorithm>
#include<math.h>
#include <iomanip>
#include<set>
#include <numeric>
#include<string>
using ll = long long;
using namespace std;


int main()
{
    ll t, n, m;
    cin >> t;
    for (int i = 0; i < t; i++){
        int n, m;
        cin >> n >> m;
        vector<ll> v(n);
        for (int j = 0; j < m; j++){
            int a, b;
            cin >> a >> b;
            v[a-1]++;
            v[b-1]++;
        }
        sort(v.begin(), v.end());
        bool yn = false;
        for (int j = 0; j < n - 1; j++){
            if (v[j] == v[j+1]){
                cout << "Yes\n";
                yn = true;
                break;
            }
        }
        if (!yn) cout << "No\n";
    }
}