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.Collections.Generic;

namespace AizuOnLine_Lesson
{
    class Program
    {
        static void Main(string[] args)
        {
            List<int> data = Program.GetData();

            int minNum = data[0];
            int maxNum = data[0];
            int diff = -1000000000;

            for (int i = 1; i < data.Count; i++)
            {
                if (data[i] < minNum)
                {
                    minNum = data[i];
                    maxNum = data[i];
                    diff = Math.Max(diff, data[i] - data[i - 1]);
                }
                else if (maxNum < data[i])
                {
                    maxNum = data[i];
                    diff = Math.Max(diff, maxNum - minNum);
                }
                else
                {
                    diff = Math.Max(diff, 0);
                }
            }

            Console.WriteLine(diff);
        }


        private static List<int> GetData()
        {
            List<int> data = new List<int>();

            int count = Convert.ToInt32(Console.ReadLine());

            for (int i = 0; i < count; i++)
            {
                data.Add(Convert.ToInt32(Console.ReadLine()));
            }

            return data;
        }
    }
}