import java.util.*;
import java.io.*;

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

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