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)

fn count_coins(x: usize) -> (usize, usize){
    let five_hundred = x / 500;
    let reminder = x % 500;
    let five = reminder / 5;
    (five_hundred, five)
}

fn main() {
    let mut buffer = String::new();
    std::io::stdin().read_line(&mut buffer).unwrap();
    let n: usize = buffer.trim_right().parse().unwrap();

    let coins = count_coins(n);
    let five_hundred = coins.0;
    let five = coins.1;
    let happiness = 1000 * five_hundred + 5 * five;
    println!("{}", happiness);
}