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: Wrong Answer)

#include<stdio.h>
int main(void)
{
  int N;
  int x, y;
  int answer;
  scanf("%d", &N);
  if(15 <= N && N <= 29){
      x = 800 * N;
      y = 200;
  }
  if(30 <= N && N <= 44){
      x = 800 * N;
      y = 400;
  }
    if(45 <= N && N <= 59){
      x = 800 * N;
      y = 600;
  }
    if(60 <= N && N <= 74){
      x = 800 * N;
      y = 800;
  }
    if(75 <= N && N <= 100){
      x = 800 * N;
      y = 1000;
  }
  answer = x - y;
  printf("%d\n", answer);
  return 0;
}