import java.util.Scanner;
public class Taxi
{
public static void main(String []agrs){
Scanner s = new Scanner(System.in);
int i = s.nextInt();
double a = 0;
if( i <= 3){
a = 8;
}
if ( i > 3 && i <= 5)
{
a = 8 + 1.2*(i - 3);
}
if (i > 5)
{
a = 10.4 + 1.5(i - 5);
}
System.out.println("你打车收取的费用为："+a);
}
}
