using System; using System.IO; using System.Linq; using System.Collections; using System.Collections.Generic; using System.Numerics; using System.Diagnostics; using System.Text; using System.Text.RegularExpressions; using System.Threading.Tasks; using static System.Math; class P { static void Main() { var val = Console.ReadLine(); Console.WriteLine(Regex.IsMatch(val, "^13+$") ? Console.ReadLine().Count(x => x == '3') : -1); } }