N,M = map(int,input().split())
E = [[] for _ in range(N)]
D = [0] * N

for i in range(M):
    a,b = map(int,input().split())
    E[a].append((b,i))
    E[b].append((a,i))
    D[a] += 1
    D[b] += 1
    if i == 0:
        s0 = a
cnt = 0

for i in range(N):
    if D[i] % 2 == 1:
        cnt += 1
        s0 = i

if cnt > 2:
    print("NO")
    exit()

cnt = 0
def dfs(u):
    global cnt
    if cnt == M:
        print("YES")
        exit()
    for v,id in E[u]:
        if nu[id]:
            nu[id] = 0
            cnt += 1
            dfs(v)
            cnt -= 1
            nu[id] = 1

nu = [1] * M
dfs(s0)
print("NO")