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>
#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; // 十分小さい値を初期値に設定
    int minv = R[0];

    for ( int i = 1; i < n; i++ ) { // ここで毎回 R[i] を読み込めば、配列は不要
        maxv = max(maxv, R[i] - minv); // 最大値を更新
        minv = min(minv, R[i]); // ここまでの最小値を保持しておく
    }

    cout << maxv << endl;

    return 0;
}