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 Kotlin (1.3.71) (judge verdict: Accepted)

import java.io.PrintWriter

fun next() = readLine()!!
fun nextInt() = next().toInt()
fun nextLong() = next().toLong()
fun nextDouble() = next().toDouble()
fun nextList() = next().split(" ")
fun nextIntList() = nextList().map(String::toInt)
fun nextLongList() = nextList().map(String::toLong)
fun nextDoubleList() = nextList().map(String::toDouble)

val pw = PrintWriter(System.out)
fun print(s: Any = "") = pw.print(s)
fun println(s: Any = "") = pw.println(s)

fun <T> Iterable<T>.join(separator: CharSequence = ", ", prefix: CharSequence = "", postfix: CharSequence = "") = joinToString(separator, prefix, postfix)
fun <T> Array<T>.join(separator: CharSequence = ", ", prefix: CharSequence = "", postfix: CharSequence = "") = joinToString(separator, prefix, postfix)

fun main(args: Array<String>) {
    main()
    pw.flush()
}


fun main() {
    val N = nextInt()
    val a = N % 1000
    println(if (a == 0) 0 else (1000 - a))
}