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 Haskell (judge verdict: Memory Limit Exceeded)

import Data.List
import Control.Applicative
import qualified Data.IntMap as M

main = do
 os <- map (tail . words) . init . lines <$> getContents
 mapM_ print (pq (M.empty) os) 

pq :: M.IntMap Int -> [[String]] -> [Int]
pq q = reverse . fst . foldl' process ([],q)

process (acc,q) [x] = (acc, M.insertWith (+) (read x) 1 q)
process (acc,q) _
 | v > 1 = (k:acc, M.adjust pred k q)
 | otherwise = (k:acc, M.delete k q)
 where (k,v) = M.findMax q