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: Accepted)

function main(input = "") {
    let N = 0 | input;
    res = N % 1000;
    if ( res > 0){
        return 1000 - res;
    } else { 
        return 0;
    }    
}

//******************************
exports.main = main;

function Main(input) {
    console.log(main(input.trim()));
}

if (process.argv[2] !== "test") {
    Main(require("fs").readFileSync("/dev/stdin", "utf8"));
}