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 PHP (7.4.4) (judge verdict: Wrong Answer)

$m = 0;

while(true){
    if(1000 * $m > $N){
        $ans = 1000 * $m - $N;
        var_dump($ans);
        return $ans;
        break;
    } else {
        $m++;
    }
}