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: Wrong Answer)

using System;

class AOJ
{
	public static void Main()
	{
		int num = int.Parse(Console.ReadLine().Trim());
		int input, min_val = 0, max_val = 0;
		for(int i = 1; i<= num; i++)
		{
			input = int.Parse(Console.ReadLine().Trim());
			if(i == 1){ min_val = input; }
			else
			{
				if(i == 2){ max_val = input - min_val; }
				else
				{
					max_val = Math.Max(max_val, input - min_val);
					min_val = Math.Min(min_val, input);
				}
			}
		}
		Console.WriteLine(max_val);
	}
}