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.BufferedReader;
import java.io.InputStreamReader;

public class Main {

	public static final int MAXN = 200000;
	public static final int MINN = 2;

	public static void main(String[] args) throws Exception {
		BufferedReader r = new BufferedReader(new InputStreamReader(System.in));
		int n = readInt(r);
		int[] price1 = new int[n];
		for(int i = 0 ; i < n ; i++) {
			price1[i] = readInt(r);
		}

		int max = -200000;
		for(int y = 0 ; y < n ; y++){
			for(int x = y+1; x < n; x++){
				if(max < price1[x] - price1[y]){
					max = price1[x] - price1[y];
				}
			}
		}
		System.out.println(max);
	}

	public static int readInt(BufferedReader r) throws Exception{
		return Integer.parseInt(r.readLine());
	}

}