using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine(Solution("1111010101111"));

    }

    public static int Solution(string s)

    {

        var number = Convert.ToInt32(s, 2);

        var steps = 0;

        while (number != 0)

        {

            if (number % 2 == 0)

            {

                number /= 2;

            }

            else

            {

                number -= 1;

            }

            steps++;

        }

        return steps;

    }

}