import java.util.*;

class Main
{
    public static void main(String[] args)
    {
        Scanner sc = new Scanner(System.in);
        
        int n = sc.nextInt();
        
       int cash = 1000;
       int count = 1;
        while (cash * count < n) {
            count++;
        }
        
        int payment = cash * count - n;
        System.out.println(payment);
    }
}
            
/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