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: Wrong Answer)

import java.io.*;

public class Main {
	public static void main(String[] args) {
		int MAX = 200000;
		int n;
		int[] R;
		
		R = new int[MAX];
		
		BufferedReader reader = new BufferedReader (new InputStreamReader(System.in));
		try{
			System.out.println("n?");
			String line = reader.readLine();
			
			n = Integer.parseInt(line);
			System.out.println("R?");
			for(int i = 0; i < n; i++ ) {
				line =reader.readLine();
				R[i] = Integer.parseInt(line);
			}
			
			int maxv = -2000000000;
			int minv = R[0];
			
			for ( int i = 0; i < n ; i++) {
				maxv = Math.max(maxv, R[i] -minv);
				minv = Math.min(minv, R[i]);
			}
			
			System.out.println(maxv);
			
		} catch (IOException e) {
			System.out.println(e);
		} catch (NumberFormatException e) {
			System.out.println("??°????????\?????????????????????");
		}
	}
}