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