N, M = map(int, raw_input().split())
deg = [0 for _ in xrange(M)]
for _ in xrange(M):
    a, b = map(int, raw_input().split())
    deg[a] += 1
    deg[b] += 1
odd = sum(d % 2 for d in deg)
print "YES" if odd == 0 or odd == 2 else "NO"