T = int(input())
for _ in range(T):
    N, M = map(int, input().split())
    G = [[] for _ in range(N)]
    cnt = [0 for _ in range(N)]
    for _ in range(M):
        u, v = map(int, input().split())
        u-=1
        v-=1
        G[u].append(v)
        G[v].append(u)
        cnt[u]+=1
        cnt[v]+=1
    S = set()
    for c in cnt:
        S.add(c)
    if len(S)==N:
        print("No")
    else:
        print("Yes")