using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static readonly Dictionary<int, int> DaysInTheMonth = new()

    {

        { 1, 31 }, // Jan

        { 2, 28 }, // Feb

        { 3, 31 }, // Mar

        { 4, 30 }, // Apr

        { 5, 31 }, // May

        { 6, 30 }, // Jun

        { 7, 31 }, // Jul

        { 8, 31 }, // Aug

        { 9, 30 }, // Sep

        { 10, 31 }, // Oct

        { 11, 30 }, // Nov

        { 12, 31 } // Dec

    };

    public static void Main()

    {

        int startMonth = 7;

        int endMonth = 5;

        var days = GetTotalDays(startMonth, endMonth);

        Console.WriteLine($"\nCounting the days in the months {startMonth} through {endMonth} results in a total of {days} days");

    }

​

    private static int GetTotalDays(int startMonth, int endMonth)

    {

        var months = DaysInTheMonth.Select(entry => entry.Key);

​

        if (endMonth >= startMonth)

        {

            months = months

                .Where(m => m >= startMonth && m <= endMonth);

        }

        else

        {

            months = months

                .Where(m => m >= startMonth || m <= endMonth);

        }

​

        int days = 0;

​

        foreach (var month in months)

        {

            Console.WriteLine($"Adding {DaysInTheMonth[month]} days (month {month})");

            days += DaysInTheMonth[month];

        }

​

        return days;

    }

}