import collections

def solve(N, M, data):
    count = collections.Counter()

    for d in data:
        count.update(d)

    oddcount = 0
    for key, val in count.items():
        if val % 2 == 1:
            oddcount += 1

    return "YES" if oddcount <= 2 else "NO"

if __name__ == '__main__':
    N, M = map(int, input().split())
    d = []
    for _ in range(0, M):
        d.append(list(map(int, input().split())))
    print(solve(N, M, d))