import sys

sys.setrecursionlimit(10 ** 6)
def MI(): return map(int, sys.stdin.readline().split())

def main():
    n,m=MI()
    deg=[0]*n
    for _ in range(m):
        a,b=MI()
        deg[a]+=1
        deg[b]+=1
    odd=sum(x%2 for x in deg)
    if odd==0 or odd==2:print("YES")
    else:print("NO")
main()