import java.util.*;

public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        
        int n = sc.nextInt();
        int m = sc.nextInt();
        
        int[] c = new int[n];
        ArrayList[] x = new ArrayList[n];
        for(int i=0; i<n; i++){
            x[i] = new ArrayList<Integer>();
        }
        
        int at = 0;
        for(int i=0; i<m; i++){
            int a = sc.nextInt();
            int b = sc.nextInt();
            x[a].add(b);
            x[b].add(a);
            c[a]++;
            c[b]++;
            at = a;
        }
        
        int con = 0;
        ArrayList<Integer> q = new ArrayList<Integer>();
        q.add(at);
        boolean[] ch = new boolean[n];
        while(q.size()>0){
            int now = q.remove(0);
            ch[now] = true;
            for(int i=0; i<x[now].size(); i++){
                int ne = (int)x[now].get(i);
                if(ch[ne]){
                    continue;
                }
                q.add(ne);
                Set<Integer> set = new HashSet<Integer>(q);
                q = new ArrayList<Integer>(set);
            }
            con++;
        }
        
        int uni = 0;
        int odd = 0;
        for(int i=0; i<n; i++){
            if(c[i]%2==1){
               odd++;
            }
            if(c[i]>0){
                uni++;
            }
        }
        
        if(con<uni){
            System.out.println("NO");
            System.exit(0);
        }
        
        if(odd==0 || odd==2){
            System.out.println("YES");
        }else{
            System.out.println("NO");
        }
    }
}