using System;

using System.Collections.Generic;

public class MinerTask

{

    public static void Main()

    {

        var input = Console.ReadLine();

        var metals = new Dictionary<string, int>();;

        while (input != "stop")

        {

            var quantity = int.Parse(Console.ReadLine());

            if (metals.ContainsKey(input))

            {

                metals[input] += quantity;

            }

            else

            {

                metals.Add(input, quantity);

            }

            input = Console.ReadLine();

        }

        foreach (var pair in metals)

        {

            Console.WriteLine("{0} -> {1}", pair.Key, pair.Value);

        }

    }

}

​