import java.util.*;

class Main
{
	public static void main(String args[]) throws Exception
	{
		Scanner in = new Scanner(System.in);
		int n=in.nextInt();
		int ans=n%1000;
		if(ans!=0)
			ans=-ans+1000;
		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