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;

class Program
{
    public static void Main(){
        var n=int.Parse(Console.ReadLine());
        var r0=int.Parse(Console.ReadLine());
        var r1=int.Parse(Console.ReadLine());
        var min=Math.Min(r0, r1);
        var result=r1-r0;
        for(var i=2; i<n; i++){
            var r=int.Parse(Console.ReadLine());
            if(r-min>result){
                result=r-min;
            }
            if(r<min){
                min=r;
            }
        }
        Console.WriteLine(result);
    }
}