codeforces 546A Soldier and Bananas

最新推荐文章于 2019-03-22 11:41:02 发布

Wzywdj

最新推荐文章于 2019-03-22 11:41:02 发布

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本文探讨了一道有趣的数学问题：一名士兵希望购买一定数量的香蕉，并且每次购买的价格成等差数列递增。文章提供了计算所需额外借款的算法，并附带了一个C++实现示例。

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

AC:

#include<bits/stdc++.h>
using namespace std;
int main()
{
    int k,n,w;
    scanf("%d%d%d",&k,&n,&w);
    int sum=0;
    for(int i=1;i<=w;i++)
        sum+=i*k;
    if(n<sum)
        printf("%d\n",sum-n);
    else
        printf("0\n");
}