import java.util.Scanner;
public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		String str=sc.nextLine();
         int a =Integer.parseInt(str);
         //int z=a/1000
		// int b = 1;
        if(a%1000==0){
          System.out.println(0);}
        
      else if(a%1000>0){
        int z=1;
        int b= a/1000;
        
            System.out.println((z+b)*1000-a);
       }
      }
        
        
	}
/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