#include <iostream>
#include <string>
#include <cstring>

int main()
{
    std::string in;
    std::cin >> in;
    
    if(*in.begin() != '1')
    {
        std::cout << -1 << std::endl;
    }
    else
    {
        int counter = 0;
        for(auto itr = in.begin() + 1; itr != in.end(); ++itr)
        {
            if(*itr != '3')
            {
                std::cout << -1 << std::endl;
                return 0;
            }
            counter++;
        }
        std::cout << (counter == 0 ?  -1 : counter) << std::endl;
    }
    return 0;
}