Problem:
MathJax.Hub.Config({ tex2jax: { inlineMath: [["$","$"], ["\\(","\\)"]], processEscapes: true }});

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: Accepted)

using System;
using System.Text;

class Program
{
    public void Proc()
    {
        int itemCount = int.Parse(Console.ReadLine());
        int[] items = new int[itemCount];
        for (int i = 0; i < itemCount;i++)
        {
            items[i] = int.Parse(Console.ReadLine());
        }

        // ??????????????????
        int min = int.MaxValue;
        int max = int.MinValue;

        for(int i=0; i<items.Length; i++)
        {
            max = Math.Max(max, items[i] - min);
            min = Math.Min(min, items[i]);
        }
        Console.WriteLine(max);
    }


    static void Main(string[] args)

    {

        Program prg = new Program();
        prg.Proc();

    }
}