using System;
using System.Linq;

public class P0476 {
    public static void Main() {
        var na = Console.ReadLine().Trim().Split(' ').Select(int.Parse).ToList();
        var mai = na[0] * na[1];
        var a = Console.ReadLine().Trim().Split(' ').Select(int.Parse).Sum();
        if(mai == a) {
            Console.WriteLine("YES");
        } else {
            Console.WriteLine("NO");
        }
    }
}