import sys
import io, os
input = io.BytesIO(os.read(0,os.fstat(0).st_size)).readline

t = int(input())
for _ in range(t):
    n, m = map(int, input().split())
    ind = [0]*n
    for i in range(m):
        a, b = map(int, input().split())
        a, b = a-1, b-1
        ind[a] += 1
        ind[b] += 1
    if len(set(ind)) == len(ind):
        print('No')
    else:
        print('Yes')