import java.util.Scanner;
public class Main
{
public static void main(String[] args)
{
Scanner in = new Scanner(System.in);
int n = in.nextInt();
int k=n/10;
int i=k/5*2;
int j=(k-(k/5)*5)/3;
System.out.println(k+i+j);
}
}
import java.util.Scanner;
public class Main
{
public static void main(String[] args)
{
Scanner in = new Scanner(System.in);
int n = in.nextInt();
int k=n/10;
int i=k/5*2;
int j=(k-(k/5)*5)/3;
System.out.println(k+i+j);
}
}