Soldier and Bananas CodeForces

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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

3 17 4

output

13

Solution : in Java

import java.util.Scanner;

public class SoldierandBananas {

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        int k = sc.nextInt();

        int n = sc.nextInt();

        int w = sc.nextInt();

        int res = (k*((w*(w+1))/2))-n;

        if(res<0){

            System.out.println(0);

        }else{

            System.out.println(res);

        }

    }

}

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