for _ in range(int(input())):

    n, m = map(int, input().split())
    a = [0 for _ in range(n)]
    for i in range(m):
        v, u = map(int, input().split())
        a[v - 1] += 1
        a[u - 1] += 1
    a.sort()
    ans = True
    for i in range(n - 1):
        if a[i] == a[i + 1]:
            ans = False
            break
    if ans:
        print("No")
    else:
        print("Yes")