import java.util.*;
import java.io.*;
import java.math.*;
import java.util.stream.Stream;

public class Main{
    /* 入出力 */
    static BufferedReader buff = new BufferedReader(new InputStreamReader(System.in));
    static StringTokenizer st;
    static PrintWriter output = new PrintWriter(System.out);
    static Scanner sc = new Scanner(System.in);
    /* 定数 */
    static final int [] y4 = {0,1,0,-1};
    static final int [] x4 = {1,0,-1,0};
    static final int  INF1 = Integer.MAX_VALUE;
    static final long INF2 = Long.MAX_VALUE;
    static final long MOD1 = (long)1e9+7;
    static final long MOD2 = 998244353;
    /* Main */
    public static void main(String[] args) throws IOException{
        int T = sc.nextInt();
        while(T-->0) {
            int n = sc.nextInt();
            int m = sc.nextInt();
            boolean ok = false;
            int [] degree = new int[n+1];
            int [] cnt = new int[n+1];
            while(m-->0) {
                int u = sc.nextInt();
                int v = sc.nextInt();
                degree[u]++;
                degree[v]++;
            }
            for(int i=1;i<=n;i++) {
                cnt[degree[i]]++;
                if(cnt[degree[i]] > 1) ok = true;
            }
            output.println(ok?"Yes":"No");
        }
        output.flush();        
    }
}