#!/usr/bin/env python3

import itertools


class UnionFind(object):

    def __init__(self, number_of_nodes):
        self.par = list(range(number_of_nodes))
        self.rank = [0] * number_of_nodes

    def root(self, node):
        if self.par[node] == node:
            return node
        else:
            r = self.root(self.par[node])
            self.par[node] = r
            return r

    def in_the_same_set(self, node1, node2):
        return self.root(node1) == self.root(node2)

    def unite(self, node1, node2):
        x = self.root(node1)
        y = self.root(node2)
        if x != y:
            if self.rank[x] < self.rank[y]:
                x, y = y, x
            self.par[y] = x
            if self.rank[x] == self.rank[y]:
                self.rank[x] += 1


def solve(num_vs, adj_list):
    uf = UnionFind(num_vs)
    for u, vs in enumerate(adj_list):
        for v in vs:
            uf.unite(u, v)
    vs = (v for v in range(num_vs) if adj_list[v])
    for u, v in itertools.product(vs, repeat=2):
        if not uf.in_the_same_set(u, v):
            return False
    degs = (len(vs) for vs in adj_list)
    num_odd_points = sum(deg % 2 for deg in degs)
    return num_odd_points == 0 or num_odd_points == 2


def main():
    n, m = (int(x) for x in input().split())
    adj_list = [set() for _ in range(n)]
    for _ in range(m):
        sa, sb = (int(x) for x in input().split())
        adj_list[sa].add(sb)
        adj_list[sb].add(sa)
    res = solve(n, adj_list)
    print("YES" if res else "NO")


if __name__ == '__main__':
    main()