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 SLDS1_1_MaximumProfit
{
    class MaximumProfit2
    {
        public static void Main()
        {
            Scanner cin = new Scanner();

            // Input
            int n = cin.myInputInt();
            int[] r = new int[n];
            for (int i = 0; i < n; i++) r[i] = cin.myInputInt();

            // Solve
            int max = -2000000000;
            int min = r[0];
            for (int i = 1; i < n; i++)
            {
                max = Math.Max(max, r[i] - min);
                min = Math.Min(min, r[i]);
            }

            // Output
            Console.WriteLine("{0}", max);
        }
    }

    class Scanner
    {
        string[] s;
        int i;

        char[] cs = new char[] { ' ' };

        public Scanner()
        {
            s = new string[0];
            i = 0;
        }

        public string myInput()
        {
            if (i < s.Length)
                return s[i++];
            string st = Console.ReadLine();
            while (st == "")
                st = Console.ReadLine();
            s = st.Split(cs, StringSplitOptions.RemoveEmptyEntries);
            i = 0;
            return s[i++];
        }

        public int myInputInt()
        {
            return int.Parse(myInput());
        }

        public long myInputLong()
        {
            return long.Parse(myInput());
        }

        public double myInputDouble()
        {
            return double.Parse(myInput());
        }
    }
}