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>
using namespace std;

int Max(int x, int y) {
    int a = x;
    if (a < y) {
        a = y;
    }
    return a;
}

int Min(int x, int y) {
    int a = x;
    if (a > y) {
    a = y;
    }
    return a;
}
int main() {
    int n;
    cin >> n;
    vector<int> data(n);
    for (int i = 0; i < n; i++) {
        cin >> data.at(i);
    }
    int max = data.at(1) - data.at(0);
    int min = data.at(0);
    for (int i = 1; i < n; i++) {
        max = Max(max, data.at(i) - min);
        min = Min(min, data.at(i));
    }
    cout << max << endl;
    return 0;
}