using System;

using System.Text.RegularExpressions;

​

public class Program

{

    public static void Main()

    {

        string input = "RESTRICTED LPN: RBM9294 FOR HOTLIST: United Auto Recovery";

        var matches = Regex.Match(input, "(ALERT LPN|RESTRICTED LPN): (.*?) FOR");

        if (matches.Success)

        {

            string plate = matches.Groups[2].Value;

            Console.WriteLine(plate);

        }

​

    }

}