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 JAVA (judge verdict: Accepted)

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main{

	public static void main(String[] args) throws NumberFormatException,
			IOException {
		 BufferedReader br = new BufferedReader(new
		 InputStreamReader(System.in));
		//BufferedReader br = new BufferedReader(new FileReader("sample.txt"));

		int n = Integer.parseInt(br.readLine());
		int[] in = new int[n];
		int max = Integer.MIN_VALUE;
		int mini = 0;
		int maxj=0;
		boolean con=false;
		
		for (int i = 0; i < n; i++)
			in[i] = Integer.parseInt(br.readLine());
		

		for (int i = 0; i < n - 1; i++) {
			if (in[i] > in[mini])continue;
			for (int j = i + 1; j < n; j++){
				if(i!=0&&con&&i<maxj){
					mini=i;
					max=in[maxj]-in[i];
					break;}
				else if(max+in[i]<in[j]){
					max=in[j]-in[i];
					mini=i;
					maxj=j;
					con=false;
				}
			}con=true;
		}
		System.out.println(max);

	}

}