import java.lang.reflect.Array;
import java.util.*;
import java.io.*;
import java.lang.*;

public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);

        int a = sc.nextInt();
        if (a%1000 == 0)
            System.out.println("0");
        else
            System.out.println(1000-(a%1000));

    }
} import java.lang.reflect.Array; Array java.lang.reflect import java.util.*; util.* java import java.io.*; io.* java import java.lang.*; lang.* java public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);

        int a = sc.nextInt();
        if (a%1000 == 0)
            System.out.println("0");
        else
            System.out.println(1000-(a%1000));

    }
} Main public static void main(String[] args){
        Scanner sc = new Scanner(System.in);

        int a = sc.nextInt();
        if (a%1000 == 0)
            System.out.println("0");
        else
            System.out.println(1000-(a%1000));

    } main {
        Scanner sc = new Scanner(System.in);

        int a = sc.nextInt();
        if (a%1000 == 0)
            System.out.println("0");
        else
            System.out.println(1000-(a%1000));

    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int a = sc.nextInt(); a sc.nextInt() sc.nextInt sc if (a%1000 == 0)
            System.out.println("0");
        else
            System.out.println(1000-(a%1000)); a%1000 == 0 a%1000 a 1000 0 System.out.println("0") System.out.println System.out System System.out "0" System.out.println(1000-(a%1000)) System.out.println System.out System System.out 1000-(a%1000) 1000 (a%1000) a 1000 String[] args args public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);

        int a = sc.nextInt();
        if (a%1000 == 0)
            System.out.println("0");
        else
            System.out.println(1000-(a%1000));

    }
} public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);

        int a = sc.nextInt();
        if (a%1000 == 0)
            System.out.println("0");
        else
            System.out.println(1000-(a%1000));

    }
} Main
import java.lang.reflect.Array;
import java.util.*;
import java.io.*;
import java.lang.*;

public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);

        int a = sc.nextInt();
        if (a%1000 == 0)
            System.out.println("0");
        else
            System.out.println(1000-(a%1000));

    }
}
