using System;

class OddMultiply
{
    static void Main()
    {

        string n = Console.ReadLine();
        int odd = 1;
        int num;

        foreach(char item in n)
        {
            if(Char.IsDigit(item) == true)
            {
                num = (int)Char.GetNumericValue(item);
                if (num % 2 == 1)
                {
                    odd *= num;
                }
            }

        }
        Console.WriteLine(odd);
    }
}