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 Rust (1.15.1) (judge verdict: Accepted)

#![allow(unused)]

use std::io::{Read, StdinLock};
use std::iter::{FromIterator, Iterator};
use std::str::{FromStr};
use std::string::String;

macro_rules! debug {
    ($($a:expr),*) => {
        println!(concat!($(stringify!($a), " = {:?}, "),*), $($a),*);
    }
}

pub fn read_bytes<T: FromIterator<char>>(s: &mut StdinLock) -> T {
    s.bytes()
        .map(|c| c.unwrap() as char)
        .skip_while(|c| c.is_whitespace())
        .take_while(|c| !c.is_whitespace())
        .collect::<T>()
}

pub fn reads(s: &mut StdinLock) -> String {
    read_bytes::<String>(s)
}

pub fn read<T: FromStr>(s: &mut StdinLock) -> T {
    reads(s).parse().ok().unwrap()
}

//==============================================================================
//
// Problem specific code
//
//==============================================================================

fn main() {
    let sin = std::io::stdin();
    let mut sin = sin.lock();

    let x: i64 = read(&mut sin);

    println!("{}", (x / 500) * 1000 + (x % 500) / 5 * 5);
}