import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        int  n = Integer.parseInt(br.readLine());
        if(n%1000==0)
            System.out.println(0);
        else
            System.out.println(1000 - (n%1000));
    }
} import java.io.BufferedReader; BufferedReader java.io import java.io.IOException; IOException java.io import java.io.InputStreamReader; InputStreamReader java.io public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        int  n = Integer.parseInt(br.readLine());
        if(n%1000==0)
            System.out.println(0);
        else
            System.out.println(1000 - (n%1000));
    }
} Main public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        int  n = Integer.parseInt(br.readLine());
        if(n%1000==0)
            System.out.println(0);
        else
            System.out.println(1000 - (n%1000));
    } main {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        int  n = Integer.parseInt(br.readLine());
        if(n%1000==0)
            System.out.println(0);
        else
            System.out.println(1000 - (n%1000));
    } BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) int  n = Integer.parseInt(br.readLine()); n Integer.parseInt(br.readLine()) Integer.parseInt Integer br.readLine() br.readLine br 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) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        int  n = Integer.parseInt(br.readLine());
        if(n%1000==0)
            System.out.println(0);
        else
            System.out.println(1000 - (n%1000));
    }
} public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        int  n = Integer.parseInt(br.readLine());
        if(n%1000==0)
            System.out.println(0);
        else
            System.out.println(1000 - (n%1000));
    }
} Main
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        int  n = Integer.parseInt(br.readLine());
        if(n%1000==0)
            System.out.println(0);
        else
            System.out.println(1000 - (n%1000));
    }
}
