N, M = map(int, input().split())
S = [True for _ in range(N)]
C = [False for _ in range(N)]
G = [[] for _ in range(N)]
for _ in range(M):
    a, b = map(int, input().split())
    S[a] = not(S[a])
    S[b] = not(S[b])
    G[a].append(b)
    G[b].append(a)
    C[a] = C[b] = True
    p = a

count = 0
for i, s in enumerate(S):
    if not s:
        count += 1
        p = i


def dfs(g, p, visited):
    visited[p] = True
    for n in g[p]:
        if not visited[n]:
            dfs(g, n, visited)

visited = [False for _ in range(N)]
dfs(G, p, visited)
print('YES' if count <= 2 and visited.count(True) == C.count(True) else 'NO')