using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine(MaxProfit(new int[]{2,4,1}));

    }

    public static int MaxProfit(int[] prices) {

         if(prices.Length == 1) return 0;

        int buyingPrice = prices[0];

        int sellingPrice = 0;

        int FinalProfit = 0;

        for(int i = 1;i < prices.Length; i++)

        {

            if(prices[i] < buyingPrice)

            {

                if(sellingPrice != 0) 

                {

                    FinalProfit += (sellingPrice - buyingPrice);

                    sellingPrice = 0;

                }

                buyingPrice = prices[i];

            }

            else

            {

                // Assuming Arr[i] > BP then that becomes selling Price

                if(sellingPrice < prices[i])

                {

                    sellingPrice = prices[i];

                    if(i == prices.Length-1) FinalProfit += (sellingPrice - buyingPrice);

                }

                else

                {

                    FinalProfit += (sellingPrice - buyingPrice);

                    buyingPrice = prices[i];

                    sellingPrice = 0;

                }

            }

            }

        return  FinalProfit;

    }

}