import java.util.*;
class Main{
public static void main(String[] args){
  Scanner sc=new Scanner(System.in);
  int n=sc.nextInt();
  for(int i=1000;;i+=1000){
    if(i>=n){
System.out.println(i-n);
      break;
    }
  }
}
}
/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