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 C (GCC 5.4.1) (judge verdict: Accepted)

#include <stdio.h>

#define MEALP 800 // meal price in yen
#define PAIDA 200 // amount given back per 15 meals

int main()
{
    int N;
    long total_given, paid_back;
    scanf("%d", &N);
    total_given = MEALP * N;
    paid_back   = N/15 * PAIDA;
    total_given -= paid_back;
    printf("%ld\n", total_given);
}