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>
#include <cmath>

using namespace std;

int main(){
    int n;
    cin >> n;
    long long a[200010], min = 10000000000, max = -10000000000;

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

        if (max < a[i] - min) { max = a[i] - min; }

        if (a[i] < min){
            min = a[i];
        }
    }

    cout << max << endl;
}