Problem:
MathJax.Hub.Config({ tex2jax: { inlineMath: [["$","$"], ["\\(","\\)"]], processEscapes: true }});

Maximum Profit

You can obtain profits from foreign exchange margin transactions. For example, if you buy 1000 dollar at a rate of 100 yen per dollar, and sell them at a rate of 108 yen per dollar, you can obtain (108 - 100) × 1000 = 8000 yen.

Write a program which reads values of a currency $R_t$ at a certain time $t$ ($t = 0, 1, 2, ... n-1$), and reports the maximum value of $R_j - R_i$ where $j > i$ .

Input

The first line contains an integer $n$. In the following $n$ lines, $R_t$ ($t = 0, 1, 2, ... n-1$) are given in order.

Output

Print the maximum value in a line.

Constraints

$2 \leq n \leq 200,000$

$1 \leq R_t \leq 10^9$

Sample Input 1

6
5
3
1
3
4
3

Sample Output 1

3

Sample Input 2

3
4
3
2

Sample Output 2

-1

Solution in Haskell (judge verdict: Memory Limit Exceeded)

-- | Main entry point to the application.
module Main where
 
import Control.Applicative
import Control.Monad
import Data.List
import Debug.Trace
import Text.Printf
import Data.Array

solve :: [Int] -> Int
solve ns = maximum $ zipWith (-) (tail ns) $ scanl1 min ns

-- | The main entry point.
main :: IO ()
main = do
    _ <- getLine
    ns <- concatMap (fmap (read :: String -> Int) . words) . lines <$> getContents
    -- let ns = [5,3,1,3,4,3]
    -- let ns = [1..200000]
    putStrLn $ show $ solve ns