using System;

using System.Globalization;

public class Program

{

    public static void Main()

    {

        Console.WriteLine(GetWeeksInMonth(new(2025, 6, 1)));

    }

    private static int GetWeeksInMonth(DateTime date)

    {

        Calendar calendar = CultureInfo.CurrentCulture.Calendar;

        DateTime firstDay = new(date.Year, date.Month, 1);

        int days = DateTime.DaysInMonth(date.Year, date.Month);

        DateTime lastDay = new(date.Year, date.Month, days);

        Console.WriteLine(lastDay);

​

        int firstWeek = calendar.GetWeekOfYear(firstDay, CalendarWeekRule.FirstDay, DayOfWeek.Monday); // firstDay.DayOfWeek is wrong

        Console.WriteLine(firstWeek);

        int lastWeek = calendar.GetWeekOfYear(lastDay, CalendarWeekRule.FirstDay, DayOfWeek.Monday); // lastDay.DayOfWeek is wrong

        Console.WriteLine(lastWeek);

​

        return (lastWeek - firstWeek) + 1;

    }   

}