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 JavaScript (judge verdict: Accepted)

//config = {input: 'tmp', newline: '\r\n'}; // win
config = {input: '/dev/stdin', newline: '\n'}; //linux

line = require('fs').readFileSync(config.input, 'ascii')
  .trim()
  .split(config.newline)
  .slice(1)
  .map(Number);

const NUM_MAX = Math.pow(10, 9);
minRi = line.shift();
max = -NUM_MAX;

for (i in line) {
  max = Math.max(max, line[i] - minRi);
  minRi = Math.min(minRi, line[i]);
}

console.log(max);