4

if __name__ == '__main__':
    N_Q = input().split(' ')
    N = int(N_Q[0])
    Q = int(N_Q[1])

    str_facts = []

    for i in range(Q):
        str_facts.append(input().split(' '))

    facts = [[0] * 2 for i in range(Q)]

    for i in range(Q):
        facts[i][0] = int(str_facts[i][0]) - 1
        facts[i][1] = int(str_facts[i][1]) - 1

    is_contains = False
    for i in range(N):
        is_contains = False
        for j in range(Q):
            if i in facts[j]:
                is_contains = True

    if is_contains:
        print("Yes")
    else:
        print("No")