for t in range(int(input())):
    n,m=map(int,input().split())
    cnt=[0]*n
    for i in range(m):
        a,b=map(int,input().split())
        cnt[a-1]+=1
        cnt[b-1]+=1
    cnt2=[0]*(m+1)
    for i in range(n):
        cnt2[cnt[i]]+=1
    if max(cnt2)>=2:
        print("Yes")
    else:
        print("No")