import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int yen = sc.nextInt();
        boolean flg = true;
        int i = 1;
        while(flg){
            
            int cg = 1000 * i - yen ;
            if(cg >=0){
                flg = false;
                System.out.println(cg);
            }
            i++;
        }
    }
}
/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz