t = int(input())
for _ in range(t):
    n, m = map(int, input().split())
    V = [0 for _ in range(n)]
    for _ in range(m):
        u, v = map(int, input().split())
        V[u - 1] += 1
        V[v - 1] += 1
    seen = set()
    flag = False
    for i in range(n):
        if V[i] in seen:
            flag = True
            break
        seen.add(V[i])
    if flag:
        print("Yes")
    else:
        print("No")