AlmostLucky.Lucky.isLucky C# (CSharp) Метод

        public bool isLucky(int n)
        {
            int sum = n.ToString().Select(x => x).Where(x => x == '4').Count();
            sum += n.ToString().Select(x => x).Where(x => x == '7').Count();
            if (sum == n.ToString().Length)
                return true;
            else
                return false;
        }

 static void Main(string[] args)
 {
     Lucky l = new Lucky();
     int n = int.Parse(Console.ReadLine());
     if (l.isLucky(n))
         Console.WriteLine("YES");
     else
     {
         bool finish = false;
         for (int i = 1; i <= n; i++)
         {
             if (l.isLucky(i) && n % i == 0)
             {
                 finish = true;
                 break;
             }
         }
         Console.WriteLine((finish) ? "YES" : "NO");
     }
     Console.ReadLine();
 }