Problem:
Score : 100 points

Problem Statement

We will buy a product for N yen (the currency of Japan) at a shop.

If we use only 1000-yen bills to pay the price, how much change will we receive?

Assume we use the minimum number of bills required.

Constraints

1 \leq N \leq 10000

N is an integer.

Input

Input is given from Standard Input in the following format:

N

Output

Print the amount of change as an integer.

Sample Input 1

1900

Sample Output 1

100

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

Sample Input 2

3000

Sample Output 2

0

We can pay the exact price.

Solution in JavaScript (Node.js 12.16.1) (judge verdict: Wrong Answer)

const main = async () => {
  const input = require('fs').readFileSync('/dev/stdin', 'UTF-8').trim()

const num = parseInt(input).toLocaleString().split(',')
const answer = 1000 - parseInt(num[num.length - 1])

if (answer === 1000) {
  console.log('1000');

} else {
  console.log(answer);

}
}

main()