def l():
    return map(int,input().split())

n,m=l()
ar=[0 for i in range(n)]

for i in range(m):
    sa,sb=l()
    ar[sa]+=1
    ar[sb]+=1

cnt=0

for i in ar:
    if i%2==1:
        cnt+=1
        
print('YES' if (cnt==0)or(cnt==2) else'NO')