import java.util.Scanner;

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

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

        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();
        sc.close();

        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();
        sc.close();

        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 sc.close() sc.close 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(0) System.out.println System.out System System.out 0 {
            System.out.println(1000-N%1000);
        } 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();
        sc.close();

        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();
        sc.close();

        if(N%1000==0){
            System.out.println(0);
        }
        else{
            System.out.println(1000-N%1000);
        }
    }
} Main
import java.util.Scanner;

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

        if(N%1000==0){
            System.out.println(0);
        }
        else{
            System.out.println(1000-N%1000);
        }
    }
}