#include <bits/stdc++.h>
using namespace std;

template <typename T>
struct graph {
	
	struct edge {
		int from, to;
		T cost;
	};
	
	vector<edge> edges;
	vector<vector<int>> g;
	int n;
	
	graph(int n) : n(n) {
		g.resize(n);
	}
	
	virtual void add(int from, int to, T cost) = 0;
};

template <typename T>
struct undirected_graph : graph<T> {
	using graph<T>::edges;
	using graph<T>::g;
	using graph<T>::n;
	
	undirected_graph(int n) : graph<T>(n) {
	}
	
	void add(int from, int to, T cost = 1) {
		assert(0 <= from && from < n && 0 <= to && to < n);
		g[from].emplace_back(edges.size());
		g[to].emplace_back(edges.size());
		edges.push_back({from, to, cost});
	}
};

int main() {
	int n, m;
	cin >> n >> m;
	undirected_graph<int> g(n);
	for (int i = 0; i < m; i++) {
		int from, to;
		cin >> from >> to;
		g.add(from, to);
	}
	int puni = 0;
	for (auto &v : g.g) {
		if (v.size() & 1) {
			puni++;
		}
	}
	cout << (puni < 3 ? "YES" : "NO") << endl;
	return 0;
}