BabaTinche NEED EDIT

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;


class BabaTinceAirlines
{
    static void Main(string[] args)
    {
        string firstClass = "6 1 2";// Console.ReadLine();
        string businessClass = "21 8 7";//Console.ReadLine();
        string economyClass = "44 12 17";//Console.ReadLine();

        string[] firstClassParameters = firstClass.Split();
        int firstDigit = int.Parse(firstClassParameters[0]);
        int secondDigit = int.Parse(firstClassParameters[1]);
        int thirdDigit = int.Parse(firstClassParameters[2]);

        string[] businessClassParameters = businessClass.Split();
        int firstDigitBusines = int.Parse(businessClassParameters[0]);
        int secondDigitBusines = int.Parse(businessClassParameters[1]);
        int thirdDigitBusines = int.Parse(businessClassParameters[2]);

        string[] economyClassParameters = economyClass.Split();
        int firstDigitEconomy = int.Parse(economyClassParameters[0]);
        int secondDigitEconomy = int.Parse(economyClassParameters[1]);
        int thirdDigitEconomy = int.Parse(economyClassParameters[2]);

        decimal sumEconomy = secondDigitEconomy * 1000M * 0.30M;
        decimal sumBusiness = secondDigitBusines * 3500M * 0.30M;
        decimal sumFirst = secondDigit * 7000 * 0.30M;

        decimal sumAll = sumEconomy + sumBusiness + sumFirst;

        decimal mealEconomy = (thirdDigitEconomy * 1000 * 0.05M);
        decimal mealBusiness = (thirdDigitBusines * 3500 * 0.05M);
        decimal mealFirst = (thirdDigit * 7000 * 0.05M);

        decimal allMeal = mealEconomy + mealBusiness + mealFirst;

        decimal allOtherEconomy = (firstDigitEconomy - secondDigitEconomy) * 1000M;
        decimal allOtherBusiness = (firstDigitBusines - secondDigitBusines) * 3500M;
        decimal allOtherFIrst = (firstDigit - secondDigit) * 7000M;

        decimal allOtherSum = allOtherEconomy + allOtherBusiness + allOtherFIrst;

        decimal firstRow = allOtherSum + sumAll + allMeal;

        Console.WriteLine(firstRow);

    }
}