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)

// 模範解答 from プログラミングコンテスト攻略のためのアルゴリズムとデータ構造 (マイナビ)

#include <iostream>
#include <algorithm>
using namespace std;
static const int MAX = 200000;

int main() {
	int R[MAX], n;

	cin >> n;
	for (int i = 0; i < n; i++) cin >> R[i];

	int maxv = -2000000000; // 問題の制約を踏まえて順分に小さい初期値
	int minv = R[0];

	for (int i = 1; i < n; i++) { // "i = 0"は初期値として使用したので"i = 1"からスタート
		maxv = max(maxv, R[i] - minv);
		minv = min(minv, R[i]);
	}

	cout << maxv << endl;
	return 0;
}