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
	$n = trim( fgets( STDIN ) );
	$nums = [];
	for( $i=0; $i<$n; $i++ ) {
		array_push( $nums, intval( trim( fgets( STDIN ) ) ) );
	}
	$profit = 1-1000000000;
	$min = $nums[0];
	for( $i=1; $i<$n; $i++ ) {
		$d = $nums[$i]-$min;
		if( $profit < $d ) {
			$profit = $d;
		}
		if( $nums[$i] < $min ) {
			$min = $nums[$i];
		}
	}

	print $profit;
?>