using System;
using System.Collections.Generic;
using System.Text;

namespace ConsoleApplication2
{
    class Program
    {
        static void Main(string[] args)
        {
            int[] n = new int[2];
            string[] strn = Console.ReadLine().Split(' ');
            int A = int.Parse(strn[0]);
            int B = int.Parse(strn[1]);

            if (A % 3 == 0)
            {
                Console.WriteLine(A);
            }
            else if (A.ToString().Contains("3"))
            {
                Console.WriteLine(A);
            }
        }
    }
}