for _ in range(int(input())):
    N, M = map(int, input().split())
    cnts = [0] * N
    for i in range(M):
        U, V = map(int, input().split())
        cnts[U - 1] += 1
        cnts[V - 1] += 1
    isO = False
    isS = [False] * N
    for c in cnts:
        isO |= isS[c]
        isS[c] = True
    print("Yes" if isO else "No")