Problem:
Score : 100 points

Problem Statement

Snuke has a favorite restaurant.

The price of any meal served at the restaurant is 800 yen (the currency of Japan), and each time a customer orders 15 meals, the restaurant pays 200 yen back to the customer.

So far, Snuke has ordered N meals at the restaurant.
Let the amount of money Snuke has paid to the restaurant be x yen, and let the amount of money the restaurant has paid back to Snuke be y yen.
Find x-y.

Constraints

1 ≤ N ≤ 100

Input

The input is given from Standard Input in the following format:

N

Output

Print the answer.

Sample Input 1

20

Sample Output 1

15800

So far, Snuke has paid 16000 yen, and the restaurant has paid back 200 yen. Thus, the answer is 15800.

Sample Input 2

60

Sample Output 2

47200

Snuke has paid 48000 yen for 60 meals, and the restaurant has paid back 800 yen.

Solution in Rust (1.15.1) (judge verdict: Accepted)

use std::io::*;

fn main() {
    let a = read();

    let m = a / 15 * 200;
    println!("{}", a * 800 - m);
}

// fn read_v() -> Vec<char> {
//     let s = stdin();
//     //    let mut s = BufReader::new(s.lock());
//     let b = s.bytes()
//         .map(|c| c.unwrap() as char)
//         .take_while(|c| !c.is_whitespace())
//         .collect();
//     b
// }

// fn read_t() -> (u32, u32) {
//     let mut s = String::new();
//     stdin().read_line(&mut s).expect("failed read_t");
//     let mut i = s.split_whitespace().map(|c| c.parse().ok().unwrap());
//     (i.next().unwrap(), i.next().unwrap())
// }

fn read() -> u32 {
    let s = stdin();
    //    let mut s = BufReader::new(s.lock());
    let b = s.bytes()
        .map(|c| c.unwrap() as char)
        .take_while(|c| !c.is_whitespace())
        .collect::<String>();
    b.parse().ok().expect("read() failed")
}