from collections import deque
N,M = map(int,input().split())
G = {i:[] for i in range(N)}
for _ in range(M):
    a,b = map(int,input().split())
    G[a].append(b)
    G[b].append(a)
C = {0:[],1:[]}
for i in range(N):
    if len(G[i])==0:continue
    C[len(G[i])%2].append(i)
if len(C[1])==0:
    visited = [0]*N
    s = C[0][0]
    visited[s] = 1
    que = deque([s])
    while que:
        i = que.popleft()
        for j in G[i]:
            if visited[j]==0:
                visited[j] = 1
                que.append(j)
    if sum(visited)==len(C[0]):
        print("YES")
    else:
        print("NO")
elif len(C[1])==2:
    s,g = C[1]
    visited = [0]*N
    visited[s] = 1
    que = deque([s])
    while que:
        i = que.popleft()
        for j in G[i]:
            if visited[j]==0:
                visited[j] = 1
                que.append(j)
    if sum(visited)==len(C[0])+2:
        print("YES")
    else:
        print("NO")
else:
    print("NO")