using System.Numerics;

public class Program
{
    public static void Main()
    {
        //int num = int.Parse(Console.ReadLine() ?? string.Empty);
        //string[] str = (Console.ReadLine() ?? string.Empty).Trim().Split(' ');
        string color = Console.ReadLine() ?? string.Empty;

        int cou = 0;
        for (int i = 1;i < color.Length;i++)
        {
            if(color[i]!='3')
            {
                Console.WriteLine(-1);
                return;
            }
            else
            {
                cou++;
            }
        }
        Console.WriteLine(cou);

    }
}