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 JavaScript (judge verdict: Wrong Answer)

function main(){
	var n = scan();
	var x = Array(n);
	rep(n, function(i){
		x[i] = +input[i];
	});

	var y;
	for(var i = n - 2; i >= 0; --i){
		if(y === undefined || y < x[i + 1] - x[i]){
			y = x[i + 1] - x[i];
		}
		x[i] = Math.max(x[i], x[i + 1]);
	}
	print(y);
	return 0;
}

function rep(n, func){
	for(var i = 0; i < n; ++i){
		func(i);
	}
}

process.stdin.resume();
process.stdin.setEncoding('utf8');

var input = '';
var input_index = 0;

function scan(type){
	if(type === 'string'){
		return input[input_index++];
	}
	else{
		return +input[input_index++];
	}
}

function print(val){
	console.log(val);
}

process.stdin.on('data', function(chunk){
	input += chunk;
});
process.stdin.on('end', function(){
	input = input.split(/\s+/);
	main();
});