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

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner();
        int n = sc.nextInt();
        int m = sc.nextInt();
        int[] counts = new int[n];
        UnionFindTree uft = new UnionFindTree(n);
        for (int i = 0; i < m; i++) {
            int x = sc.nextInt();
            int y = sc.nextInt();
            counts[x]++;
            counts[y]++;
            uft.unite(x, y);
        }
        int judge = 0;
        HashSet<Integer> parents = new HashSet<>();
        for (int i = 0; i < n; i++) {
            judge += counts[i] % 2;
            if (counts[i] > 0) {
                parents.add(uft.find(i));
            }
        }
        if (judge <= 2 && parents.size() == 1) {
            System.out.println("YES");
        } else {
            System.out.println("NO");
        }
    }
    
    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 (x == parents[x]) {
                return x;
            } else {
                return parents[x] = find(parents[x]);
            }
        }
        
        public boolean same(int x, int y) {
            return find(x) == find(y);
        }
        
        public void unite(int x, int y) {
            if (!same(x, y)) {
                parents[find(x)] = find(y);
            }
        }
    }
    
}
class Scanner {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    StringTokenizer st = new StringTokenizer("");
    StringBuilder sb = new StringBuilder();
    
    public Scanner() throws Exception {
        
    }
    
    public int nextInt() throws Exception {
        return Integer.parseInt(next());
    }
    
    public long nextLong() throws Exception {
        return Long.parseLong(next());
    }
    
    public double nextDouble() throws Exception {
        return Double.parseDouble(next());
    }
    
    public String next() throws Exception {
        while (!st.hasMoreTokens()) {
            st = new StringTokenizer(br.readLine());
        }
        return st.nextToken();
    }
    
}