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;

namespace ALDS1_1_D
{
    public class Program
    {
        public static void Main(string[] args)
        {
            var n = long.Parse(Console.ReadLine());
            var r = new long[n];
            for (int i = 0; i < n; i++)
            {
                r[i] = long.Parse(Console.ReadLine());
            }

            long maxValue = long.MinValue;
            long minValue = r[0];

            for(int i = 1; i < n; i++)
            {
                maxValue = Math.Max(maxValue, r[i] - minValue);
                minValue = Math.Min(minValue, r[i]);
            }

            Console.WriteLine(maxValue);
        }
    }
}