import java.util.*;
 
public class Main
{
  public static void main(String[]args)
  {
 	Scanner console = new Scanner(System.in);
    int n = console.nextInt();
    n = n % 1000;
    if(n == 0)
    {
    	System.out.print(n);
    }
    else
    {
    	int answer = 1000 - n;
    	System.out.print(answer);
    }
  }
}
/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