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: Time Limit Exceeded)

#include <iostream>

using namespace std;

int main() {
    int i,j,sa = -1000000000,n,r[200000];

    cin >> n;

    for(i = 0;i < n;i++){
        cin >> r[i];
    }

    for(n--;n > 0;n--){
        for(i = 0;i < n;i++){
            if(sa < r[n] - r[i]){
                sa = r[n] - r[i];
            }
        }
    }

    cout << sa << endl;
   
    return 0;
}