using System;

public class Solution

{

    public static void Main()

    {

        int number = int.Parse(Console.ReadLine());

        while (number < 0)

        {

            Console.WriteLine("Enter positive integer");

            number = int.Parse(Console.ReadLine());

        }

        Solution S = new Solution();

        int gap = S.FindLongestGap(number);

        Console.WriteLine("Binary Gap = {0}", gap);

    }

    public int FindLongestGap(int number)

    {   

        string binary = ConvertToBinary(number);

        int currentCount = 0, maxCount = 0;

        for (int i = 0; i < binary.Length; i++)

        {

            if (binary[i] == '0')

            {

                if (i == binary.Length - 1)

                {

                    break;  

                }

                currentCount = 1;

                for (int j = i + 1; j < binary.Length; j++)

                {

                    if (binary[j] == '0')

                    {

                        currentCount += 1;

                        if (j == binary.Length - 1)

                        {

                            currentCount = 0;

                            break;

                        }                   

                    }

                    else

                    {

                        i = j;

                        break;  

                    }

                }

                if (currentCount > maxCount)

                {

                    maxCount = currentCount;

                }

            }

        }

        return maxCount;

    }

    public string ConvertToBinary(int number)

    {

        string binaryNum = string.Empty;

        int remainder = 0;

        while (number > 0)

        {

            remainder = number % 2;

            number = number / 2;

            binaryNum = remainder.ToString() + binaryNum;

        }

        return binaryNum;

    }

}