using System;

public class Program

{

    public static void Main()

    {

        int[] flights = new int[1]{15};

        int steps = GetStrides(flights,2);

        Console.WriteLine(steps);

        flights = new int[2]{15,15};

        steps = GetStrides(flights,2);

        Console.WriteLine(steps);

        flights = new int[7]{5,11,9,13,8,30,14};

        steps = GetStrides(flights,3);

        Console.WriteLine(steps);

    }

    public static int GetStrides(int[] flights, int stepsPerStride){

        int steps = 0;

        foreach(var flight in flights){

            steps += flight / stepsPerStride + flight % stepsPerStride;

        }

        int stepsForLandings = (flights.Length - 1) * 2;

        return steps + stepsForLandings;

    }

}