using System;
using System.Numerics;
class BinaryТoDecimalNumber
{
    static void Main()
    {
        string txt = Console.ReadLine();
        long result = 0;
        BigInteger number = BigInteger.Parse(txt);
        long answer= 0;
        for (int i = 0; i <= txt.Length; i++)
        {
            BigInteger devide = number % 10;
            number  = number / 10;
            if (devide == 0)
            {
                result = 0;
            }
            if (devide == 1)
            {
                result = (long)Math.Pow(2, i);
            }
            answer += result;
        }
        Console.WriteLine(answer);
    }
}