using System;

using System.Globalization;

using System.Linq;

using System.Collections.Generic;

​

using System.Text.RegularExpressions;

​

public class Program

{

        public static void Main()

    {

        //Console.WriteLine( DateTime.TryParseExact("2007", formats.ToArray(), CultureInfo.InvariantCulture, DateTimeStyles.None, out var result));

        var regEx = new Regex("([a-zA-Z]{3}.) (\\d\\d\\d\\d)");

        var aprilWithDot = "Apr. 2022";

        var april = "April 2022";

        var mayWithDot = "May. 2022";

        var may = "May 2022";

        var juneWithDot = "Jun. 2022";

        var june = "June 2022";

        Console.WriteLine( $" {aprilWithDot} - match > {regEx.IsMatch(aprilWithDot)}" );

        Console.WriteLine( $" {april} - match > {regEx.IsMatch(april)}" );

​

        Console.WriteLine( $" {mayWithDot} - match > {regEx.IsMatch(mayWithDot)}" );

        Console.WriteLine( $" {may} - match > {regEx.IsMatch(may)}" );

        Console.WriteLine( $" {juneWithDot} - match > {regEx.IsMatch(juneWithDot)}" );

        Console.WriteLine( $" {june} - match > {regEx.IsMatch(june)}" );

​

    }

}