import java.util.*;
public class Main {
	public static void main(String[] args) {
		Scanner in = new Scanner(System.in);
		int  n = in.nextInt();
		int  rem = n%1000;
	//	int div = n%1000;
		if(n%1000==0){
			System.out.println(0);
			}
			else{
				int div = n/1000+1;
				int ans= div*1000 - n;
					System.out.println(ans);
				}
	
	}
}
/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