Soldier and Bananas Solution

 A. Soldier and Bananas

time limit per test

1 second

memory limit per test

256 megabytes

input

standard input

output

standard output

A soldier wants to buy w bananas in the shop. He has to pay k dollars for the first banana, 2k dollars for the second one and so on (in other words, he has to pay i·k dollars for the i-th banana).

He has n dollars. How many dollars does he have to borrow from his friend soldier to buy w bananas?

Input

The first line contains three positive integers k, n, w (1  ≤  k, w  ≤  1000, 0 ≤ n ≤ 109), the cost of the first banana, initial number of dollars the soldier has and number of bananas he wants.

Output

Output one integer — the amount of dollars that the soldier must borrow from his friend. If he doesn't have to borrow money, output 0.

Examples

input

Copy

3 17 4

output

Copy

13

      Solution:

      

1. import java.util.Scanner;
2.  
3. public class SoldierandBananas {
4.  
5. public static void main(String[] args) {
6. // TODO Auto-generated method stub
7. Scanner sc = new Scanner(System.in);
8. int k = sc.nextInt(),n = sc.nextInt(),w = sc.nextInt();
9. int sum = 0;
11. for(int i =1;i<=w;i++)
12. sum += i*k;
14. if(n>sum)
15. System.out.println(0);
16. else
17. System.out.println(sum-n);
18. }
19.  
20. }