import java.util.Scanner;

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];
        
        for(int i=0; i<m*2; i++){
            c[sc.nextInt()]++;
        }
        
        int odd = 0;
        for(int i=0; i<n; i++){
            if(c[i]%2==1){
               odd++;
            }
        }
        
        if(odd==0 || odd==2){
            System.out.println("YES");
        }else{
            System.out.println("NO");
        }
    }
}