#define  _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <algorithm>
#include <utility>
#include <functional>
#include <cstring>
#include <queue>
#include <stack>
#include <math.h>
#include <iterator>
#include <vector>
#include <string>
#include <set>
#include <math.h>
#include <iostream>
#include <random>
#include<map>
#include <iomanip>
#include <time.h>
#include <stdlib.h>
#include <list>
#include <typeinfo>
#include <list>
#include <set>
#include <cassert>
#include<fstream>
#include <unordered_map>
#include <cstdlib>
using namespace std;
#define Ma_PI 3.141592653589793
#define eps 0.00000000000000000000000001
#define LONG_INF 3000000000000000000
#define GOLD 1.61803398874989484820458
#define MAX_MOD 1000000007
#define REP(i,n) for(long long i = 0;i < n;++i)                                                                             
#define seg_size 524288
int used[200000] = {};
vector<int> vertexs[200000];
int visited[200000] = {};
int main() {
	int n, m;
	cin >> n >> m;
	for (int i = 0;i < m;++i) {
		int a, b;
		cin >> a >> b;
		used[a]++;
		used[b]++;
		vertexs[a].push_back(b);
		vertexs[b].push_back(a);
	}
	int foo = 0;
	for (int i = 1;i <= n;++i) {
		if (vertexs[i].size() != 0 && visited[i] == false) {
			visited[i] = true;
			foo++;
			queue<int> wow;
			wow.push(i);
			while (wow.empty() == false) {
				int ta = wow.front();
				wow.pop();
				for (int i = 0;i < vertexs[ta].size();++i) {
					if (visited[vertexs[ta][i]] == false) {
						visited[vertexs[ta][i]] = true;
						wow.push(vertexs[ta][i]);
					}
				}
			}
		}
	}
	if (foo >= 2) {
		cout << "NO" << endl;
		return 0;
	}
	int tmp = 0;
	for (int i = 0;i <= n;++i) {
		if (used[i] % 2 == 1) {
			tmp++;
		}
	}
	if (tmp >= 3) {
		cout << "NO" << endl;
	}
	else {
		cout << "YES" << endl;
	}
	return 0;
}