#define _GLIBCXX_DEBUG
#include <bits/stdc++.h>
using namespace std;

int main() {
  int T; cin >> T;
  for(int i = 0; i < T; i++){
    int N, M; cin >> N >> M;
    vector<int> S(N+1,0);
    S[0] = 1000000000;
    for(int j = 0; j < M; j++){
      int V1, V2; cin >> V1 >> V2;
      S[V1]++, S[V2]++;
    }
    sort(S.begin(), S.end());
    for(int j = 0; j < N; j++){
      if(S[j] == 1000000000){
        cout << "No" << endl;
      }
      if(S[j] == S[j+1]){
        cout << "Yes" << endl;
        break;
      }
    }
  }
}