using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace _4.Exam_Shopping
{
    class Program
    {
        static void Main(string[] args)
        {
            Dictionary<string, int> shop = new Dictionary<string, int>();

            while (true)
            {
                string input = Console.ReadLine();
                if (input.Equals("exam time")) break;
                string[] command = input.Split(' ');
                if (input == "shopping time") continue;
                string product = command[1];
                int quantity = int.Parse(command[2]);
                if (command[0].Equals("stock"))
                {
                    if (!shop.ContainsKey(product))
                    {
                        shop.Add(product, quantity);
                    }
                    else
                    {
                        shop[product] += quantity;
                    }
                }
                else if (command[0].Equals("buy"))
                {
                    if (!shop.ContainsKey(product))
                    {
                        Console.WriteLine($"{product} doesn't exist");
                    }
                    else if (shop.ContainsKey(product))
                    {
                        int stock = shop[product];
                        if (stock == 0)
                        {
                            Console.WriteLine($"{product} out of stock");
                            break;
                        }
                        else if (quantity > stock)
                        {
                            shop[product] = 0;
                        }
                        else
                        {
                            shop[product] -= quantity;
                        }
                    }
                }
            }
            foreach (var item in shop)
            {
                if (item.Value == 0)
                {
                    continue;
                }
                Console.WriteLine($"{item.Key} -> {item.Value}");
            }

        }
    }
}