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)

#include <iostream>
#include <vector>

int main(int const argc, char const** argv){
  int n;
  std::cin >> n;
  std::vector<int> vec(n);
  for(int i = 0; i<n; ++i){
    std::cin >> vec[i];
  }

  int max = -2147483648;
  int r;
  for(int i = 0; i<n; ++i){
    for(int j = i + 1; j<n; ++j){
      r = vec[j] - vec[i];
      if(max<r){
	max = r;
      }
    }
  }
  std::cout << max << std::endl;
}