def main():
    T = int(input())
    for _ in range(T):
        N,M = map(int,input().split())
        G = [[] for _ in range(N)]
        for i in range(M):
            u,v = map(int,input().split())
            u-=1;v=-1
            G[u].append(v)
            G[v].append(u)
        s = set([])
        for i in range(N):
            t = len(G[i])
            if t in s:
                print("Yes")
                break
            else:
                s.add(t)
        else:
            print("No")


if __name__ == '__main__':
    main()