using System;

public class Program

{

    public static void Main()

    {

        string hostName = "B1";

        string[] buildingCode = {"B1","B2","B3","B4"};

        string[] buildingName = {"Building 1", "Building 2", "Building 3", "Building 4"};

        if (Array.Exists(buildingCode, element => element == hostName))

        {

             Console.Write(buildingName[Array.IndexOf(buildingCode, hostName)]);

        }

        else

        {

             Console.Write("Error!");

        }

    }

}