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 <stdio.h>
#include <stdlib.h>

int Benefit(int *,int *);

int main() {
  int *price_array;
  int n;
  int benefit;
  int max_benefit;
  int i,j;

  scanf("%d",&n);
  price_array = (int *)malloc(n * sizeof(int));
  for(i=0;i<n;i++) {
    scanf("%d",price_array+i);
  }

  for(i=0;i<n;i++) {
    for(j=i+1;j<n;j++) {
      benefit = Benefit(price_array+i,price_array+j);
      if(j==1) max_benefit = benefit;
      else
      if(max_benefit < benefit) {
        max_benefit = benefit;
      }
    }
  }

  printf("%d\n",max_benefit);

  return 0;
}

int Benefit(int *x,int *y) {
  return *y-*x;
}