n = int(input())

for i in range(n):
    N,M = map(int, input().split())
    d = {i:0 for i in range(1,N+1)}
    for k in range(M):
        for j in list(map(int, input().split())):
            a = d[j]
            d[j] = a + 1

    if len(d.values()) != len(set(d.values())):
        print('Yes')
    else:
        print('No')