#include <bits/stdc++.h>
using namespace std;
int main() {
  int t;
  cin >> t;
  vector<string> ans;
  while (t--) {
    int n , m;
    cin >> n >> m;
    vector<int> c(n , 0);
    for (int i = 0; i < m; i++) {
      int a , b;
      cin >> a >> b;
      a--; b--;
      c[a]++;
      c[b]++;
    }
    sort(c.begin() , c.end());
    bool ok = false;
    for (int i = 0; i < n - 1; i++) {
      if (c[i] == c[i + 1]) {
        ok = true;
        break;
      }
    }
    if (ok) ans.push_back("Yes");
    else ans.push_back("No");
  }
  for (int i = 0; i < ans.size(); i++) {
    cout << ans[i] << endl;
  }
  return 0;
}