import java.util.Scanner;
public class Main{
 public static void main(String[] args){
  Scanner sc=new Scanner(System.in);
  int x=sc.nextInt();
  if(x>=0){
   if(x<=4){
    System.out.println(5*x);
   }else if(x<=12){
    System.out.println(5/4*x+4);
   }else{
     System.out.println("error");
   }
  }else{
   System.out.println("error");
  }
 }
}