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 C++ (judge verdict: Accepted)

#include<iostream>
using namespace std;

int main(){
	long long int a[200000] = {}, maxw = 1, maxt = -1000000000;
	int n;
	cin >> n;

	for (int i = 0; i < n; i++){
		cin >> a[i];
	}
	for (int l = 0; l < n; l++){
		if (maxw < a[n-l-1]){
			maxw = a[n-l-1];
		}
		if (maxw-a[n-l-2] > maxt) maxt = maxw-a[n-l-2];
	}

	cout << maxt << "\n";

	return 0;
}