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;
using System.Text;

class Program
{
	static void Main(string[] args)
	{
		// 行数
		int n = int.Parse(Console.ReadLine()); 

		List<long> rList = new List<long>();
		for (int i = 0; i < n; i++)
		{
			rList.Add(long.Parse(Console.ReadLine()));
		}

		long max = 0;

		for (int i = 0; i < n; i++)
		{
			long ri = rList[i];
			for (int j = i + 1; j < n; j++)
			{
				long rj = rList[j];
				if (i == 0 && j == 1 || max < rj - ri)
				{
					max = rj - ri;
				}
			}	
		}

		System.Console.WriteLine(max);
	}
}