import java.util.*;
import java.io.*;

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int m = sc.nextInt();
        int[] counts = new int[n];
        UnionFindTree uft = new UnionFindTree(n);
        HashSet<Integer> set = new HashSet<>();
        for (int i = 0; i < m; i++) {
            int x = sc.nextInt();
            int y = sc.nextInt();
            counts[x]++;
            counts[y]++;
            uft.unite(x, y);
            set.add(x);
            set.add(y);
        }
        boolean flag = true;
        int parent = -1;
        for (int x : set) {
            int y = uft.find(x);
            if (parent != -1 && parent != y) {
                flag = false;
                break;
            }
            parent = y;
        }
        int od = 0;
        for (int i = 0; i < n; i++) {
            if (counts[i] % 2 == 1) {
                od++;
            }
        }
        if (od > 2 || !flag) {
            System.out.println("NO");
        } else {
            System.out.println("YES");
        }
    }
    
    static class UnionFindTree {
        int[] parents;
        
        public UnionFindTree(int size) {
            parents = new int[size];
            for (int i = 0; i < size; i++) {
                parents[i] = i;
            }
        }
        
        public int  find(int x) {
            if(parents[x] == x) {
                return x;
            } else {
                return parents[x] = find(parents[x]);
            }
        }
        
        public void unite(int x, int y) {
            int xx = find(x);
            int yy = find(y);
            if (xx == yy) {
                return;
            }
            parents[xx] = yy;
        }
    }
}