#include<bits/stdc++.h>
#include <atcoder/all>
#ifdef LOCAL
#include <debug_print.hpp>
#define debug(...) debug_print::multi_print(#__VA_ARGS__, __VA_ARGS__)
#else
#define debug(...) (static_cast<void>(0))
#endif
using namespace atcoder;
using mint=modint998244353;
using namespace std;
using ll=long long;
using ul=unsigned long long;
int dx[8] = {-1, 1, 0, 0, -1, -1, 1, 1};
int dy[8] = {0, 0, -1, 1, -1, 1, -1, 1};
using Graph=vector<vector<int>>;
int op(ll a,ll b){return int(a+b);}
int e(){return 0;}
int main(){
    int T;
    cin>>T;
    while(T--){
        int N,M;
        cin>>N>>M;
        Graph G(N);
        for(int i=0;i<M;i++){
            int u,v;
            cin>>u>>v;
            u--,v--;
            G[u].push_back(v);
            G[v].push_back(u);
        }
        set<int>st;
        for(auto a:G)st.insert(a.size());
        cout<<(st.size()!=N?"Yes":"No")<<endl;
    }
}