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# (Mono 4.6.2.0) (judge verdict: Accepted)

#pragma warning disable
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System;
using System.Collections;

class E { static void Main() { new J(); } }
class J
{
	class Node { public int size; }
	int Size(Node t) => t?.size ?? 0;
	void F3() => Console.WriteLine();
	int F() { return int.Parse(Console.ReadLine()); }
	int[] G() { return Console.ReadLine().Split(new char[] { ' ', '\t' }, StringSplitOptions.RemoveEmptyEntries).Select(int.Parse).ToArray(); }
	public J()
	{
		Console.SetOut(new StreamWriter(Console.OpenStandardOutput()) { AutoFlush = false });
		var N = F();
		Console.WriteLine(800 * N - 200 * (N / 15));
		Console.Out.Flush();
	}
	long GCD(long a, long b)
	{
		var n = (ulong)Math.Abs(a); var m = (ulong)Math.Abs(b);
		if (n == 0) return (long)m; if (m == 0) return (long)n;
		int zm = 0, zn = 0;
		while ((n & 1) == 0) { n >>= 1; zn++; }
		while ((m & 1) == 0) { m >>= 1; zm++; }
		while (m != n)
		{
			if (m > n) { m -= n; while ((m & 1) == 0) m >>= 1; }
			else { n -= m; while ((n & 1) == 0) n >>= 1; }
		}
		return (long)n << Math.Min(zm, zn);
	}
}
class MultiSortedSet<T> : IEnumerable<T>, ICollection<T>
{
	public static Comparison<T> DefaultComparison<T>() => (x, y) => Comparer<T>.Default.Compare(x, y);
	public IComparer<T> Comparer { get; private set; }
	private SortedSet<T> keys;
	private Dictionary<T, int> mult;
	public int Multiplicity(T item) { return mult[item]; }
	public int Count { get; private set; }
	public MultiSortedSet(IComparer<T> comp)
	{
		keys = new SortedSet<T>(Comparer = comp);
		mult = new Dictionary<T, int>();
	}
	public MultiSortedSet(Comparison<T> comp) : this(Comparer<T>.Create(comp)) { }
	public MultiSortedSet() : this(DefaultComparison<T>()) { }
	public void Add(T item) { Add(item, 1); }
	private void Add(T item, int num)
	{
		Count += num;
		if (!keys.Contains(item)) { keys.Add(item); mult.Add(item, num); }
		else mult[item] += num;
	}
	public void AddRange(IEnumerable<T> list) { foreach (var x in list) Add(x); }
	public bool Remove(T item)
	{
		if (!keys.Contains(item)) return false;
		Count--;
		if (mult[item] == 1) { keys.Remove(item); mult.Remove(item); }
		else mult[item]--;
		return true;
	}
	public bool Overlaps(IEnumerable<T> other) { return keys.Overlaps(other); }
	public bool IsSupersetOf(IEnumerable<T> other) { return keys.IsSupersetOf(other); }
	public bool IsSubsetOf(IEnumerable<T> other) { return keys.IsSubsetOf(other); }
	public bool IsProperSubsetOf(IEnumerable<T> other) { return keys.IsProperSubsetOf(other); }
	public bool IsProperSupersetOf(IEnumerable<T> other) { return keys.IsProperSupersetOf(other); }
	public void ExceptWith(IEnumerable<T> other) { foreach (var x in other) if (Contains(x)) Remove(x); }
	public void IntersectWith(IEnumerable<T> other)
	{
		var next = new MultiSortedSet<T>(Comparer);
		foreach (var x in other) if (Contains(x) && !next.Contains(x)) next.Add(x, mult[x]);
		keys = next.keys; mult = next.mult;
	}
	public void CopyTo(T[] array) { CopyTo(array, 0); }
	public void CopyTo(T[] array, int index) { foreach (var item in array) array[index++] = item; }
	public void CopyTo(T[] array, int index, int count) { var i = 0; foreach (var item in array) { if (i++ >= count) return; array[index++] = item; } }
	public bool Contains(T item) { return keys.Contains(item); }
	public void Clear() { keys.Clear(); mult.Clear(); Count = 0; }
	public IEnumerator<T> Reverse() { foreach (var x in keys.Reverse()) for (var i = 0; i < mult[x]; i++) yield return x; }
	public IEnumerator<T> GetEnumerator() { foreach (var x in keys) for (var i = 0; i < mult[x]; i++) yield return x; }
	IEnumerator IEnumerable.GetEnumerator() { return GetEnumerator(); }
	public T Max { get { return keys.Max; } }
	public T Min { get { return keys.Min; } }
	public bool IsReadOnly { get { return false; } }
}