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

namespace MyCompiler {
    class Program {
        public static void Main(string[] args) 
        {
            Console.WriteLine("Hello world!");
            reverse(new string[] {"John Locke","Thomas Aquinas","David Hume","Rene Descartes"}, "ASC");
            reverse(new string[]  {"Paul Erdos","Leonhard Euler","Carl Gauss"}, "DESC");
            reverse(new string[]  {}, "DESC");
            //reverse(null, "DESC");
        }
        
        public static void reverse(string[] arr,string str)
        {
            //if(arr == null) return new string[]{};
            SortedDictionary<string,string> sd = new SortedDictionary<string,string>();
            List<string> lis = new List<string>();
            foreach(string ele in arr)
            {
                sd.Add(ele.Split(' ')[1],ele.Split(' ')[0]);
            }
            foreach(KeyValuePair<string,string> item in sd)
            {
                lis.Add(item.Value +" "+ item.Key);
            }
            List<string> lis2 = new List<string>(lis);
            lis2.Reverse();
            Console.WriteLine(string.Join(" || ",str == "ASC"?lis : lis2));
        }
    }
}