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 Go (1.14.1) (judge verdict: Wrong Answer)

package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

/* 一つ読み */
func scanText() string {
	sc.Scan()
	return sc.Text()
}
func scanInt() int {
	sc.Scan()
	a, err := strconv.Atoi(sc.Text())
	if err != nil {
		fmt.Println(err)
	}
	return a
}
func scanFloat() float64 {
	sc.Scan()
	a, err := strconv.ParseFloat(sc.Text(), 64)
	if err != nil {
		fmt.Println(err)
	}
	return a
}

/* 複数読み */
func scanTextSlice(n int) []string {
	a := make([]string, n)
	for i := 0; i < n; i++ {
		a[i] = scanText()
	}
	return a
}
func scanSlice(n int) []int {
	a := make([]int, n)
	for i := 0; i < n; i++ {
		a[i] = scanInt()
	}
	return a
}
func scanFloatSlice(n int) []float64 {
	a := make([]float64, n)
	for i := 0; i < n; i++ {
		a[i] = scanFloat()
	}
	return a
}

var sc = bufio.NewScanner(os.Stdin)

func main() {
	sc.Split(bufio.ScanWords)
	n := scanInt()
	bill := (n /  1000) + 1

	fmt.Println(bill * 1000 - n)  
	

}