BookLibrary

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

namespace BookLibrary
{
    class MainClass
    {
        public static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());

            Dictionary<string, double> library = new Dictionary<string, double>();

            for (int i = 0; i < n; i++)
            {
                List<string> input = Console.ReadLine().Split(' ').ToList();
                string title = input[0];
                string author = input[1];
                string publisher = input[2];
                string date = input[3];
                string isbn = input[4];
                double price = double.Parse(input[5]);

                if (!library.ContainsKey(author))
                {
                    library.Add(author, 0);
                }
                library[author] += price;
            }
            foreach (var entry in library.OrderByDescending(x => x.Value).ThenBy(x => x.Key))
            {
                Console.WriteLine("{0} -> {1:F2}", entry.Key, entry.Value);
            }
        }
    }
}