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)

//  ALDS1_1_D
using System;

namespace Aizu
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            int[] prices = new int[n];

            for (int i = 0; i < n; i++)
            {
                prices[i] = int.Parse(Console.ReadLine());
            }

            int maxv = GetMaxDifferential(n, prices);

            /*
            int maxv = prices[1] - prices[0];
            int minv = prices[0];

            for (int i = 1; i < n; i++)
            {
                maxv = Math.Max(maxv, prices[i] - minv);
                minv = Math.Min(minv, prices[i]);
            }
            */

            Console.WriteLine(maxv);

        }

        static int GetMaxDifferential(int n, int[] values)
        {
            int maxv = values[1] - values[0];
            int minv = values[0];

            for (int i = 1; i < n; i++)
            {
                maxv = Math.Max(maxv, values[i] - minv);
                minv = Math.Min(minv, values[i]);
            }

            return maxv;
        }
    }
}