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)

using System;
using System.Collections.Generic;

class program
{
    public static void Main()
    {
        var n = long.Parse(Console.ReadLine());
        var R = new long[n];

        for (var i = 0; i < n; i++)
        {
            R[i] = long.Parse(Console.ReadLine());
        }

        long max = long.MinValue;
        for (var i = 0; i < n - 1; i++)
        {
            for (var j = i + 1; j < n; j++)
            {
                max = max < R[j] - R[i] ? R[j] - R[i] : max;
                // Console.WriteLine(max + "i" + i + "j" + j);
            }
        }

        Console.WriteLine(max);
    }
}