using System;

public class Program

{

    public static void Main()

    {

        int index;

        int[]a = new int[]{3,7,9,12,15};

        index = int.Parse(Console.ReadLine());

        Console.WriteLine(Summary(a,index));

    }

public static int Summary (int[]a , int index)

{

    int x=0;

    for(int i=0; i<=index; i++)

    {

        x += a[i];

    }

    return x;

}

}