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