using System;

public class Program

{

    public static void Main()

    {

        string s = urlify("Please Save Me    ", 14);

        Console.WriteLine(s);

    }

    public static string urlify(string s, int n)

    {

        char[] c = new char[s.Length];

        c = s.ToCharArray();

        int index = 0; int i = 0;

        int space = 0;

        for ( i = 0 ; i < n ; i ++)

        {

            if (c[i] ==  ' ')

            {

            space++;

            }

        }

        index = n + space * 2;

        for (i = n- 1 ; i >= 0 ; i --)

        if (c[i] ==  ' ')

            {

            c[index - 1] = '0';

            c[index - 2] = '2';

            c[index - 3] = '%';

            index = index - 3;

            }   

​

        else

        {

            c[index-1] = c[i];

            index = index - 1;

        }

    return new string(c);

    }

}