t=int(input())

for i in range(t):
    n,m=map(int,input().split())
    ns=[[] for i in range(n+1)]
    s=set()
    for i in range(m):
        a,b=map(int,input().split())
        ns[a].append(b)
        ns[b].append(a)
    for i in range(1,n+1):
        s.add(len(ns[i]))
        if len(s) != i:
            print('Yes')
            break
    else:
        print('No')