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: Accepted)

using System;
using System.Collections.Generic;
using System.Globalization;
using System.IO;
using System.Linq;
using System.Text;

namespace LogicSummoner
{
    class Program
    {
        static void Main(string[] args)
        {
            var N = GetNumber();

            var max = int.MinValue;
            var min = int.MaxValue;
            var prev = 0;
            for (int i = 0; i < N; i++)
            {
                var now = GetNumber();
                if (i != 0)
                {
                    min = Math.Min(min, prev);
                    max = Math.Max(max, now - min);
                }

                prev = now;
            }

            System.Console.WriteLine(max);
        }

        //static StreamReader Console = new StreamReader("input.txt");

        static int GetNumber()
        {
            return int.Parse(Console.ReadLine().Trim());
        }

        static double GetDounble()
        {
            return double.Parse(Console.ReadLine().Trim());
        }

        static int[] GetNumbersInt(int n = 0)
        {
            return Console.ReadLine().Trim().Split(new[] { " " }, StringSplitOptions.RemoveEmptyEntries).Select(x => int.Parse(x)).ToArray();
        }

        static long[] GetNumbersLong(int n = 0)
        {
            return Console.ReadLine().Trim().Split(new[] { " " }, StringSplitOptions.RemoveEmptyEntries).Select(x => long.Parse(x)).ToArray();
        }

        static double[] GetNumbersDouble(int n = 0)
        {
            return Console.ReadLine().Trim().Split(new[] { " " }, StringSplitOptions.RemoveEmptyEntries).Select(x => double.Parse(x)).ToArray();
        }

        static string[] GetStrings(int n = 0)
        {
            return Console.ReadLine().Trim().Split(new[] { " " }, StringSplitOptions.RemoveEmptyEntries).ToArray();
        }
    }
}