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: Time Limit Exceeded)

import java.io.*;

class Main {
    public static void main (String[] args) throws Exception {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int n = Integer.parseInt(br.readLine());
        int[] price = new int[n];
        int i, j;
        int max = (int) -Math.pow(10, 9);

        for (i = 0; i < n; i++) {
            price[i] = Integer.parseInt(br.readLine());
        }
        for (i = 0; i < n-1; i++) {
            for (j = i+1; j < n; j++) {
                if (price[j] - price[i] > max) {
                    max = price[j] - price[i];
                }
            }
        }
        System.out.println(max);
    }
}