AtCoder Beginner Contest 173 A - Payment

A - Payment

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Time Limit: 2 sec / Memory Limit: 1024 MB

Score : $100100$ points

Problem Statement

We will buy a product for $\mathrm{NN}$ yen (the currency of Japan) at a shop.

If we use only $10001000$-yen bills to pay the price, how much change will we receive?

Assume we use the minimum number of bills required.

Constraints

• $\mathrm{1\le N\le 100001\le N\le 10000}$
• $\mathrm{NN}$ is an integer.

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Input

Input is given from Standard Input in the following format:

$\mathrm{NN}$

Output

Print the amount of change as an integer.

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Sample Input 1 Copy

Copy

1900

Sample Output 1 Copy

Copy

100

We will use two $1000$-yen bills to pay the price and receive $100$ yen in change.

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Sample Input 2 Copy

Copy

3000

Sample Output 2 Copy

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0

We can pay the exact price.

题意：给你一个数，算出找零的数(其实原文更容易看懂)

解题思路：对n用1k求余如果余数为0则不用找钱(给的钱刚好为1k的整数倍)，否则就要找1k-n%1k的零钱

代码如下：

#include<cstdio>
int main(void)
{
    int n;
    while(~scanf("%d",&n))
    printf("%d\n",n%1000==0?0:1000-n%1000);
    return 0;
}