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