using System;

using System.Text.RegularExpressions;

public class Program

{

    public static void Main()

    {

        Console.WriteLine(Regex.IsMatch("7869 BM",@"[0-9]{4}\s*[a-zA-Z]{2}"));

        Console.WriteLine(Regex.IsMatch("7869BM",@"[0-9]{4}\s*[a-zA-Z]{2}"));

    }

}