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 Go (1.6) (judge verdict: Accepted)

package main

import "fmt"

func main() {
	var x int
	fmt.Scan(&x)
	sho := x / 500
	var oldresult int = 0
	var amari int
	var yen50 int
	var result int
	for i := 0; i < sho+1; i++ {
		amari = x - sho*500
		yen50 = amari / 5
		result = i*1000 + yen50*5
		if result > oldresult {
			oldresult = result
		}
		if result < oldresult {
			break
		}
	}
	fmt.Println(oldresult)
}