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>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <limits.h>

#define REP(i,n) for(i=0;i<n;i++)

//prototype declaration
int iin();
long long llin();
double din();
char cin();
void stin(char *s);
void iout(int i);
void llout(long long i);
void dout(double i);
void cout(char c);
void stout(char *s);
int gcd(int a, int b);
int lcm(int a, int b);
long long llgcd(long long a, long long b);
long long lllcm(long long a, long long b);
int asc(const void *a, const void *b);
int desc(const void *a, const void *b);

//main function
int main() {
    int n = iin();
    iout(n * 800 - (int)(n / 15) * 200);
    return 0;
}

//body function
int iin() {
    int i;
    scanf("%d", &i);
    return i;
}

long long llin() {
    long long i;
    scanf("%lld", &i);
    return i;
}

double din() {
    double i;
    scanf("%lf", &i);
    return i;
}

char cin() {
    char c;
    scanf("%c", &c);
    return c;
}

void stin(char *s) {
    scanf("%s", s);
}

void iout(int i) {
    printf("%d\n", i);
}

void llout(long long i) {
    printf("%lld\n", i);
}

void dout(double i) {
    printf("%lf\n", i);
}

void cout(char c) {
    printf("%c\n", c);
}

void stout(char *s) {
    printf("%s\n", s);
}

/*
    int型の最大公約数
*/

int gcd(int a, int b) {
    int r;

    if (a < b) {
        r = a;
        a = b;
        b = r;
    }

    r = a % b;
    while (r != 0) {
        a = b;
        b = r;
        r = a % b;
    }

    return b;
}

/*
    int型の最小公倍数
*/

int lcm(int a, int b) {
    int r = llgcd(a, b);
    a /= r;
    return a * b;
}

/*
    long long型の最大公約数
*/

long long llgcd(long long a, long long b) {
    long long r;

    if (a < b) {
        r = a;
        a = b;
        b = r;
    }

    r = a % b;
    while (r != 0) {
        a = b;
        b = r;
        r = a % b;
    }

    return b;
}

/*
    long long型の最小公倍数
*/

long long lllcm(long long a, long long b) {
    long long r = llgcd(a, b);
    a /= r;
    return a * b;
}

/*
    int型の昇順用比較関数
*/

int asc(const void *a, const void *b) {
    return *(int *)a - *(int *)b;
}

/*
    int型の降順用比較関数
*/

int desc(const void *a, const void *b) {
    return *(int *)b - *(int *)a;
}