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;

class Program
{
	static void Main(string[] args)
	{
		int n = int.Parse(Console.ReadLine());
		long[] r = new long[n];
		for (int i = 0; i < n; i++)
		{
			r[i] = long.Parse(Console.ReadLine());
		}

		long max = -1000000000000;

		for(int i=0; i<n; i++)
		{
			for(int j=i+1; j<n; j++)
			{
				long x = r[j] - r[i];
				if(x > max)
				{
					max = x;
				}
			}
		}

		Console.WriteLine(max);
	}
}