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