Problem:
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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 PHP (judge verdict: Accepted)

<?php

fscanf(STDIN, '%d', $count);
$max=1-10**9;
for($i=0;$i<$count;$i++) {
  fscanf(STDIN, '%d',$n);
  if($i===0){
    $min=$n;
  }else {
    if($n-$min>$max){
      $max=$n-$min;
    }
  }
  if($min>$n) {
    $min=$n;
  }
}
echo $max . PHP_EOL;