P03MaxMinElement

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

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

            Stack<int> stack = new Stack<int>();

            for (int i = 0; i < n; i++)
            {
                string input = Console.ReadLine();

                if (input.Length == 1)
                {
                    int[] array = input.Split().Select(int.Parse).ToArray();

                    int command = array[0];

                    while (stack.Any())
                    {
                        if (command == 2)
                        {
                            stack.Pop();
                            break;
                        }
                        else if (command == 3)
                        {
                            Console.WriteLine(stack.Max());
                            break;
                        }
                        else if (command == 4)
                        {
                            Console.WriteLine(stack.Min());
                            break;
                        }
                    }
                }
                else
                {
                    int[] array = input.Split().Select(int.Parse).ToArray();

                    int command = array[0];
                    int number = array[1];

                    stack.Push(number);
                }
            }

            Console.WriteLine(string.Join(", ", stack));
        }
    }
}