from typing import List

class UnionFind:
    """0-indexed"""

    def __init__(self, n):
        self.n = n
        self.parent = [-1] * n
        self.__group_count = n

    def unite(self, x, y) -> bool:
        """xとyをマージ"""
        x = self.root(x)
        y = self.root(y)
        if x == y:
            return False

        self.__group_count -= 1

        if self.parent[x] > self.parent[y]:
            x, y = y, x

        self.parent[x] += self.parent[y]
        self.parent[y] = x
        return True

    def is_same(self, x, y) -> bool:
        """xとyが同じ連結成分か判定"""
        return self.root(x) == self.root(y)

    def root(self, x) -> int:
        """xの根を取得"""
        if self.parent[x] < 0:
            return x
        else:
            # 経路圧縮あり
            # self.parent[x] = self.root(self.parent[x])
            # return self.parent[x]
            # 経路圧縮なし
            return self.root(self.parent[x])

    def size(self, x) -> int:
        """xが属する連結成分のサイズを取得"""
        return -self.parent[self.root(x)]

    def all_sizes(self) -> List[int]:
        """全連結成分のサイズのリストを取得 O(N)
        """
        sizes = []
        for i in range(self.n):
            size = self.parent[i]
            if size < 0:
                sizes.append(-size)
        return sizes

    def groups(self) -> List[List[int]]:
        """全連結成分の内容のリストを取得 O(N・α(N))"""
        groups = dict()
        for i in range(self.n):
            p = self.root(i)
            if not groups.get(p):
                groups[p] = []
            groups[p].append(i)
        return list(groups.values())

    @property
    def group_count(self) -> int:
        """連結成分の数を取得 O(1)"""
        return self.__group_count

N, M = map(int, input().split())
v = [0]*N
vv = set()
uf = UnionFind(N)
for i in range(M):
    a, b = map(int, input().split())
    vv.add(a)
    vv.add(b)
    uf.unite(a, b)
    v[a] += 1
    v[b] += 1

if uf.group_count != 1+(N-len(vv)):
    print('NO')
else:
    cnt = 0
    for i in range(N):
        if v[i]%2==1:
            cnt += 1
    if cnt>=3:
        print('NO')
    else:
        print('YES')