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 C (judge verdict: Time Limit Exceeded)

// Maximum profit
#include <stdio.h>
#include <stdlib.h>

int main() {
  int a[200000];
  int i, j, n, max;
  // input
  scanf("%d", &n);
  for(i = 0; i < n; i++) {
    scanf("%d", &a[i]);
  }

  // search max
  max = a[n - 1] - a[n - 2];
  for(i = n - 1; i >= 0; i--) {
    for(j = i - 1; j >= 0; j--) {
      if(a[i] - a[j] > max) max = a[i] - a[j];
    }
  }

  // output
  printf("%d\n", max);

  
  return 0;
}