Problem:
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Priority Queue

A priority queue is a data structure which maintains a set $S$ of elements, each of with an associated value (key), and supports the following operations:

$insert(S, k)$: insert an element $k$ into the set $S$

$extractMax(S)$: remove and return the element of $S$ with the largest key

Write a program which performs the $insert(S, k)$ and $extractMax(S)$ operations to a priority queue $S$.
The priority queue manages a set of integers, which are also keys for the priority.

Input

Multiple operations to the priority queue $S$ are given. Each operation is given by "insert $k$", "extract" or "end" in a line. Here, $k$ represents an integer element to be inserted to the priority queue.

The input ends with "end" operation.

Output

For each "extract" operation, print the element extracted from the priority queue $S$ in a line.

Constraints

The number of operations $\leq 2,000,000$

$0 \leq k \leq 2,000,000,000$

Sample Input 1

insert 8
insert 2
extract
insert 10
extract
insert 11
extract
extract
end

Sample Output 1

8
10
11
2

Solution in C# (judge verdict: Time Limit Exceeded)

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

namespace _20170410_AOJ
{
    class ALDS1_9C
    {
        static void Main(string[] args)
        {
            List<int> S = new List<int>();
            for (;;)
            {
                string[] command = Console.ReadLine().Split(' ');
                if (command[0] == "end")
                {
                    break;
                }

                switch (command[0])
                {
                    case "insert":
                        Insert(S, int.Parse(command[1]));
                        break;
                    case "extract":
                        int max = ExtractMax(S);
                        Console.WriteLine(max);
                        break;
                }
            }

            Console.ReadLine();
        }

        static void Insert(List<int> list, int k)
        {
            list.Add(k);
        }

        static int ExtractMax(List<int> list)
        {
            int max = list.Max();
            list.Remove(max);
            return max;
        }
    }
}