    import java.util.Scanner;
    public class Main{
    	public static void main(String[] args) {
    		// TODO 自動生成されたメソッド・スタブ
    		Scanner sc = new Scanner(System.in);
    		int N = sc.nextInt();
    		int c = 0;
    		while(N  >  c) {
    			c = c + 1000;
    		}
    			c= c-N;
    		System.out.println(c);
    	}
     
    }
/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