using System.Collections.Generic;
using System;

public class Hello
{
    static void Main()
    {
        var t = int.Parse(Console.ReadLine().Trim());
        while (t-- > 0)
        {
            string[] line = Console.ReadLine().Trim().Split(' ');
            var n = int.Parse(line[0]);
            var m = int.Parse(line[1]);
            var a = new int[n];
            for (int i = 0; i < m; i++)
            {
                line = Console.ReadLine().Trim().Split(' ');
                var p = int.Parse(line[0]) - 1;
                var q = int.Parse(line[1]) - 1;
                a[p]++;
                a[q]++;
            }
            getAns(a);
        }
    }
    static void getAns(int[] a)
    {
        var hs = new HashSet<int>();
        foreach (var x in a)
        {
            if (!hs.Add(x)) { Console.WriteLine("Yes"); return; }
        }
        Console.WriteLine("No");
    }
}