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++11 (judge verdict: Accepted)

#include <iostream>
#include <limits>

int main() {
    int n{};
    std::cin >> n;
    if(n<2) return 1;
    int val[n]{}, mins[n-1]{}, max{std::numeric_limits<int>().min()}, maxdiff{max};
    for(auto i=0; i<n; i++) {
        int v{};
        std::cin >> v;
        val[i] = v;
        mins[i] = v;
        if(i>0) mins[i] = (mins[i-1]<v) ? mins[i-1] : mins[i];
    }
    for(auto i=n-1; i>0; i--) {
        max = (val[i]>max) ? val[i] : max;
        int diff{max-mins[i-1]};
        maxdiff = (diff>maxdiff) ? diff : maxdiff;
    }
    std::cout << maxdiff << std::endl;
}