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: Accepted)

<?php
# 入力部
// fscanf(STDIN, "%d", $a);
// fscanf(STDIN, "%d %d %d", $n, $x, $t);
// fscanf(STDIN, "%s", $s);
fscanf(STDIN, "%d", $n);

# 処理部
// for ($i = 0; $n > $x * $i; $i++) {
// }
// if (strpos($s, 'RRR') !== false) {
//   $r = 3;
// } elseif (strpos($s, 'RR') !== false) {
//   $r = 2;
// } elseif (strpos($s, 'R') !== false) {
//   $r = 1;
// } else {
//   $r = 0;
// }
// $s = "No";
// if ($x >= 30) {
//   $s = "Yes";
// }
for ($i = 0; $i * 1000 < $n; $i++) {
}

# 出力部
// echo $r . "\n";
echo ($i * 1000) - $n . "\n";