using System;
using System.Linq;

public class Hoge{
    public static void Main(string[] args){
        var line = Console.ReadLine();
        var ar = line.ToCharArray();        
        var i = ar.Count(e=> e == '3');
        if( i == 0 || i != line.Length -1){
            Console.WriteLine("-1");
        }else{
            Console.WriteLine(i);
        }
    }
}