import java.util.Scanner;
 
public class Main {
  public static void main(String[] args) {
    Scanner scanner = new Scanner(System.in);
    int num = scanner.nextInt();
    int answer = 0;
    
    for (int i = 1; i < 11; i++) {
      int bill = 1000*i;
      if (num > bill) {
      	continue;  
      } else {
       	answer = bill-num;
        break;
      }
    }
    System.out.println(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