using System;
using System.Collections.Generic;
using System.IO;
using System.Text;
using System.Text.RegularExpressions;

namespace KizhiPart1
{
    public static class Hello
    {
        public static void Main()
        {
            Console.OutputEncoding = Encoding.UTF8;
            TextWriter writer = new StringWriter();
            var interpreter = new Interpreter(writer);

            interpreter.ExecuteLine("set a 5");
            interpreter.ExecuteLine("set a 6");
            interpreter.ExecuteLine("print a");


            Console.Read();
        }
    }
    public class Interpreter
    {
        public TextWriter _writer;
        private readonly Dictionary<string, int> _variables;
        private readonly Queue<string> _output;
        private readonly string pattern = @"^([a-zA-Z]+|)$";

        public Interpreter(TextWriter writer)
        {
            _variables = new Dictionary<string, int>();
            _output = new Queue<string>();
            _writer = writer;
        }

        public void ExecuteLine(string command)
        {
            _writer = new StringWriter();

            var sequence = command.Split(' ');

            if (sequence.Length > 3 || sequence.Length < 2)
            {

                _output.Clear();
                _writer.Write($"Неизвестная команда: ");
                foreach (var item in sequence)
                {
                    _writer.Write(item + ' ');
                }
                _writer.WriteLine();
                return;
            }

            else if (sequence.Length == 3)
            {
                bool success = int.TryParse(sequence[2], out int value);

                if (Regex.IsMatch(sequence[1], pattern) && success && value > 0)
                {
                    if (sequence[0] == "set")
                    {
                        if (!_variables.ContainsKey(sequence[1]))
                        {
                            _variables.Add(sequence[1], value);
                            return;
                        }
                        else
                        {
                            _variables[sequence[1]] = value;
                            return;
                        }
                    }

                    else if (sequence[0] == "sub")
                    {
                        if (_variables.ContainsKey(sequence[1]))
                        {
                            if (_variables[sequence[1]] - value > 0)
                            {
                                _variables[sequence[1]] -= value;
                                return;
                            }
                            else
                            {
                                _output.Clear();
                                _writer.WriteLine("Результат операции sub должен быть натуральным числом");
                                return;
                            }
                        }
                        else
                        {
                            _output.Clear();
                            _writer.WriteLine("Переменная отсутствует в памяти");
                            return;
                        }
                    }
                    else
                    {
                        _output.Clear();
                        _writer.Write($"Неизвестная команда: ");
                        foreach (var item in sequence)
                        {
                            _writer.Write(item + ' ');
                        }
                        _writer.WriteLine();
                        return;
                    }
                }
                else
                {
                    _output.Clear();
                    _writer.Write($"Неизвестная команда: ");
                    foreach (var item in sequence)
                    {
                        _writer.Write(item + ' ');
                    }
                    _writer.WriteLine();
                    return;
                }
            }

            else if (sequence.Length == 2)
            {
                if (Regex.IsMatch(sequence[1], pattern))
                {
                    if (sequence[0] == "print")
                    {
                        if (_variables.ContainsKey(sequence[1]))
                        {
                            _output.Enqueue(_variables[sequence[1]].ToString());
                        }
                        else
                        {
                            _output.Clear();
                            _writer.WriteLine("Переменная отсутствует в памяти");
                            return;
                        }
                    }

                    else if (sequence[0] == "rem")
                    {
                        if (_variables.ContainsKey(sequence[1]))
                        {
                            _variables.Remove(sequence[1]);
                            return;
                        }
                        else
                        {
                            _output.Clear();
                            _writer.WriteLine("Переменная отсутствует в памяти");
                            return;
                        }
                    }
                }
                else
                {
                    _output.Clear();
                    _writer.Write($"Неизвестная команда: ");
                    foreach (var item in sequence)
                    {
                        _writer.Write(item + ' ');
                    }
                    _writer.WriteLine();
                    return;
                }
            }

            foreach (var item in _output)
            {
                _writer.WriteLine(item);
            }
            _output.Clear();
        }
    }
}