import sys
readline = sys.stdin.readline

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