"""

https://yukicoder.me/problems/no/1563

次数は、0以上N-1以下

"""

from sys import stdin

TT = int(stdin.readline())

for loop in range(TT):

    N,M = map(int,stdin.readline().split())

    lis = [0] * N
    for i in range(M):
        v,u = map(int,stdin.readline().split())
        v -= 1
        u -= 1

        lis[v] += 1
        lis[u] += 1

    ans = "No"
    lis.sort()

    for i in range(N-1):
        if lis[i+1] == lis[i]:
            ans = "Yes"

    print (ans)