from collections import defaultdict

N, M = map(int, input().split())
adj_dict = defaultdict(list)

for _ in range(M):
    Sa_i, Sb_i = map(int, input().split())
    adj_dict[Sa_i].append(Sb_i)
    adj_dict[Sb_i].append(Sa_i)

degree_even, degree_odd = 0, 0

for node in adj_dict:
    d = len(adj_dict[node])
    
    if d % 2 == 0:
        degree_even += 1
    else:
        degree_odd += 1

if degree_odd == 0 or degree_odd == 2:
    print('YES')
else:
    print('NO')