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
{
    static void Main(string[] args)
    {

        int res = -1000000000;
        List<int> a = new List<int>();
        int n = int.Parse(Console.ReadLine());
        a.Add(int.Parse(Console.ReadLine()));

        for (int j = 0; j < n-1;j++)
        {
            string s = Console.ReadLine();
            if (string.IsNullOrEmpty(s)) break;
            a.Add(int.Parse(s));

            for (int i = 0; i < a.Count - 1;i++)
            {
                if (a[a.Count -1] - a[i] > res)
                {
                    res = a[a.Count - 1] - a[i];
                }
            }
        }

        Console.WriteLine("{0}",res);

	}



}