import java.util.*;
public class Main {

	public static void main(String[] args) {
		        Scanner sc = new Scanner(System.in);
		        
		        int n = sc.nextInt();
		        int temp = n / 1000 * 1000;
		        int result = temp == n ? 0 : temp + 1000 - n;
		        System.out.println(result);

	}

}

/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