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 <bits/stdc++.h>

int main()
{
    int N;
    std::cin >> N;
    std::vector<int> R(N);
    R.reserve(1000000000);
    for (int i = 0; i < N; i++) {
        std::cin >> R[i];
    }

    int minv, maxv;
    minv = R[0];
    maxv = R[1] - minv;
    for (int j = 1; j < N; j++) {
        if (R[j] - minv > maxv) {
            maxv = R[j] - minv;
        }
        if (minv > R[j]) {
            minv = R[j];
        }
    }

    std::cout << maxv << std::endl;
}