import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.Scanner;

public class Main {
	
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		final int N = sc.nextInt();
		final int M = sc.nextInt();
		
		ArrayList<HashSet<Integer>> adj = new ArrayList<HashSet<Integer>>();
		for(int i = 0; i < N; i++){ adj.add(new HashSet<Integer>()); }
		
		int[] degs = new int[N];
		for(int i = 0; i < M; i++){
			final int a = sc.nextInt();
			final int b = sc.nextInt();
			
			adj.get(a).add(b);
			adj.get(b).add(a);
			
			degs[a]++; degs[b]++;
		}
		
		boolean[] visited = new boolean[N];
		visited[0] = true;
		LinkedList<Integer> queue = new LinkedList<Integer>();
		queue.add(0);
		while(!queue.isEmpty()){
			final int node = queue.poll();
			
			for(final int next : adj.get(node)){
				if(visited[next]){ continue; }
				
				visited[next] = true;
				queue.add(next);
			}
		}
		//System.out.println(Arrays.toString(visited));
		
		for(int i = 0; i < N; i++){
			if(degs[i] > 0 && !visited[i]){
				System.out.println("NO");
				return;
			}
		}
		
		int odd_count = 0;
		for(int i = 0; i < N; i++){
			if(degs[i] % 2 == 1){ odd_count++; }
		}
		
		if(odd_count == 0 || odd_count == 2){
			System.out.println("YES");
		}else{
			System.out.println("NO");
		}
	}
}