using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace yukicoderTest
{
    class Program
    {
        static void Main(string[] args)
        {
            string str = Console.ReadLine();
            int cnt = 0;
            if(str.Substring(0,1)==1.ToString())
            {
                for(int i=1;i<str.Length;i++)
                {
                    if(str.Substring(i,1)==3.ToString())
                    {
                        cnt++;
                    }
                    else
                    {
                        cnt = -1;
                        break;
                    }
                }
            }
            Console.WriteLine(cnt);
        }
    }
}