import java.util.Scanner;
public class Main{
	public static void main(String[] agrs){
		
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int satu = 1000;
		while(true){
			if(satu - n < 0){
				satu += 1000;
			}
			else{
				System.out.print(satu - n);
				break;
			}
		}
	}
}
/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