import sys
readline = sys.stdin.readline

class UnionFind(object):
    def __init__(self, n=1):
        self.par = [i for i in range(n)]
        self.rank = [0 for _ in range(n)]
        self.size = [1 for _ in range(n)]

    def find(self, x):
        if self.par[x] == x:
            return x
        else:
            self.par[x] = self.find(self.par[x])
            return self.par[x]

    def union(self, x, y):
        x = self.find(x)
        y = self.find(y)
        if x != y:
            if self.rank[x] < self.rank[y]:
                x, y = y, x
            if self.rank[x] == self.rank[y]:
                self.rank[x] += 1
            self.par[y] = x
            self.size[x] += self.size[y]

    def is_same(self, x, y):
        return self.find(x) == self.find(y)

    def get_size(self, x):
        x = self.find(x)
        return self.size[x]

N, M = map(int, readline().split())
G = [0] * N
U = UnionFind(N)
for i in range(M):
    u, v = map(int, readline().split())
    G[u] += 1
    G[v] += 1
    U.union(u, v)
    
odd = 0
cnt = 0
maxv = 0
for i in range(N):
    if G[i] % 2:
        odd += 1
    if G[i]:
        cnt += 1
    maxv = max(maxv, U.get_size(i))
    
if odd <= 2 and maxv == cnt:
    print("YES")
else:
    print("NO")