using System;
using System.Collections.Generic;
using System.Linq;

public class Test
{
static void Main(string[] args)
{
    var strwords = getLastWord("write LINQ queries to do THE following TASK");
    foreach (string str in strwords)
        Console.WriteLine(str);
    Console.ReadLine();
}

static IEnumerable<string> getLastWord(string str)
{           
    var upper =  str.Split(' ')
                .Where(s => String.Equals(s, s.ToUpper(),
                            StringComparison.Ordinal)).Reverse().Take(1);

    return upper;

}
}