def solve():
  N,M=map(int,input().split())
  C=[0]*N
  for i in range(M):
    a,b=map(int,input().split())
    C[a-1]+=1
    C[b-1]+=1
  if len(set(C))==N:
    print('No')
  else:
    print('Yes')

for t in range(int(input())):
  solve()