using System;

using System.Linq;

using System.Collections.Generic;

using System.Collections.Immutable;

public class Program

{

    public static void Main()

    {

        var list1 = new List<string>(){"  a   ", "b"};

        var list2 = list1.Select(elem => elem.Trim().ToUpperInvariant()).ToImmutableList();

        foreach (var elem in list2)

            Console.WriteLine(elem);

    }

}