C#: Number of days in the specified month and year

using System;

public class Example19
{
    // Main method, entry point of the program
    static void Main()
    {
        // Constants for months
        const int July = 7;
        const int Feb = 2;

        // Get the number of days in July 2016 (a regular year)
        int daysInJuly = System.DateTime.DaysInMonth(2016, July);
        Console.WriteLine(daysInJuly);

        // Get the number of days in February 2013 (not a leap year)
        // The output will be 28 as 2013 was not a leap year
        int daysInFeb = System.DateTime.DaysInMonth(2013, Feb);
        Console.WriteLine(daysInFeb);

        // Get the number of days in February 2004 (a leap year)
        // The output will be 29 as 2004 was a leap year
        int daysInFebLeap = System.DateTime.DaysInMonth(2004, Feb);
        Console.WriteLine(daysInFebLeap);
    }
}