class Program
{
    static void Main(string[] args)
    {
        string num = Console.ReadLine()!;
        num = num.TrimStart('1');
        int count = 0;

        foreach (char c in num)
        {
            if (c == '3')
            {
                count++;
            }
            else
            {
                Console.WriteLine(-1);
                return;
            }
        }
        Console.WriteLine(count);
    }
}