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(dead_code)]
#![allow(unused_variables)]
#![allow(unused_variables)]

use std::io::stdin;
use std::str::FromStr;

fn read<T: FromStr>() -> T {
    let mut str = String::new();
    stdin().read_line(&mut str).ok();
    str.trim().parse().ok().unwrap()
}

fn read_vec<T: FromStr>() -> Vec<T> {
    let mut str = String::new();
    stdin().read_line(&mut str).ok();
    str.trim().split_whitespace().map(|e| e.parse().ok().unwrap()).collect()
}

fn read_n_vec<T: FromStr>(n: u32) -> Vec<Vec<T>> {
    let mut v_outer = Vec::new();
    for _ in 0..n {
        let v_inner = read_vec();
        v_outer.push(v_inner);
    }
    v_outer
}

fn main() {
    let x : u64 = read();
    let n_500 = x / 500;
    let n_5 = (x - 500*n_500) / 5;

    println!("{}", n_500*1000 + n_5*5);
}