using System;

public class Program

{

    public static void Main()

    {

        var date = DateTime.Now;

        var firstDayOfMonth = new DateOnly(date.Year, date.Month, 1);

        var lastDayOfMonth = firstDayOfMonth.AddMonths(1).AddDays(-1);

        Console.WriteLine($"First day of this month: {firstDayOfMonth}, last day of this month: {lastDayOfMonth}");

    }

}