t = int(input())
for i in range(t):
    n, m = map(int, input().split())
    g = [0] * n
    for i in range(m):
        u, v = map(int, input().split())
        g[u-1] += 1
        g[v-1] += 1

    g.sort()
    for i in range(n-1):
        if g[i] == g[i+1]:
            print("Yes")
            break
    else:
        print("No")