import java.util.*;

class Main {
    ArrayList<Integer>[] graph;
    @SuppressWarnings("unchecked")
    Main() {
	Scanner scan = new Scanner(System.in);
	int n = scan.nextInt();
	this.graph = new ArrayList[n];
	for (int i = 0; i < n; ++i) {
	    this.graph[i] = new ArrayList();
	}
	int m = scan.nextInt();
	for (int i = 0; i < m; ++i) {
	    int sa = scan.nextInt();
	    int sb = scan.nextInt();
	    this.graph[sa].add(sb);
	    this.graph[sb].add(sa);
	}
	int numberOfOddVertices = 0;
	for (int i = 0; i < n; ++i) {
	    if (graph[i].size() % 2 != 0) {
		numberOfOddVertices += 1;
	    }
	}
	if (numberOfOddVertices > 2) {
	    System.out.println("NO");
	    return;
	}
	// Henga renketu ka douka siraberu
	int start = 0;
	for (int i = 0; i < n; ++i) {
	    if (graph[i].size() >= 1) {
		start = i;
		break;
	    }
	}
	boolean[] visited = new boolean[n];
        Queue<Integer> queue = new ArrayDeque();
	queue.add(start);
	while (queue.size() >= 1) {
	    int vertex = queue.poll();
	    if (visited[vertex]) {
	        continue;
	    }
	    visited[vertex] = true;
	    for (int target: this.graph[vertex]) {
		queue.add(target);
	    }
	}
	for (int i = 0; i < n; ++i) {
	    if (graph[i].size() >= 1 && !visited[i]) {
		System.out.println("NO");
		return;
	    }
	}
	System.out.println("YES");
    }
    public static void main(String[] args) {
	new Main();
    }
}