Problem:
Score : 200 points

Problem Statement

Takahashi loves gold coins. He gains 1000 happiness points for each 500-yen coin he has and gains 5 happiness points for each 5-yen coin he has. (Yen is the currency of Japan.)

Takahashi has X yen. If he exchanges his money so that he will gain the most happiness points, how many happiness points will he earn?

(We assume that there are six kinds of coins available: 500-yen, 100-yen, 50-yen, 10-yen, 5-yen, and 1-yen coins.)

Constraints

0 \leq X \leq 10^9

X is an integer.

Input

Input is given from Standard Input in the following format:

X

Output

Print the maximum number of happiness points that can be earned.

Sample Input 1

1024

Sample Output 1

2020

By exchanging his money so that he gets two 500-yen coins and four 5-yen coins, he gains 2020 happiness points, which is the maximum number of happiness points that can be earned.

Sample Input 2

0

Sample Output 2

0

He is penniless - or yenless.

Sample Input 3

1000000000

Sample Output 3

2000000000

He is a billionaire - in yen.

Solution in C# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
using System.IO;

    class Program
    {
        static void Main(string[] args)
        {
            var money = long.Parse(Console.ReadLine());
            var ret = 0;
            var after = money;

            while(true)
            {
                var tmp = after - 500;
                if(tmp < 0)
                {
                    break;
                }
                ret += 1000;
                after = tmp;
            }

            while (true)
            {
                var tmp = after - 5;
                if (tmp < 0)
                {
                    break;
                }
                ret += 5;
                after = tmp;
            }
            MyConsoleWrightLine(ret.ToString());
        }

        private static void MyConsoleWrightLine(string str)
        {
            var sw = new StreamWriter(Console.OpenStandardOutput()) { AutoFlush = false };
            Console.SetOut(sw);

            Console.WriteLine(str);

            Console.Out.Flush();
        }
}