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 AOJapps
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            int R = int.Parse(Console.ReadLine());
            int min = R;
            int ans = -1000000000;
            for (int i=1; i < n; i++)
            {
                R = int.Parse(Console.ReadLine());
                ans = Max2(ans, R - min);
                min = Min2(min, R);
            }
            Console.WriteLine(ans);
        }

        static int Min2(int a, int b)
        {
            if (a < b) { return a; } else { return b; }
        }

        static int Max2(int a, int b)
        {
            if (a < b) { return b; } else { return a; }
        }
    }
}