using System;
using System.Text.RegularExpressions;
 
public class Test
{
	public static void Main()
	{
                string[] data = {"TE33", "FR56", "not", "blahblahAJ00blah"};
 
                foreach(string myString in data) {
		    if(Regex.IsMatch(myString, "^[A-Za-z]{2}[0-9]{2}$")) {
                        Console.WriteLine("{0} matches", myString);
                    } else {
                        Console.WriteLine("{0} doesn't match", myString);
                    }
                }
	}
}

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