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: Accepted)

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

#define max(x,y)  (x > y) ? x:y
#define min(x,y)  (x < y) ? x:y

int main(){
  int n;
  int maxv,minv;
  int i;
  int *R;

  scanf("%d",&n);
  R = (int *)malloc(sizeof(int) * n);

  for (i = 0;i < n;i++)
    scanf("%d",&R[i]);

  maxv = R[1] - R[0];
  minv = R[0];

  for (i = 1;i < n;i++){
    maxv = max(maxv,R[i] - minv);
    minv = min(minv,R[i]);
  }

  printf("%d\n",maxv);
  free(R);
  
  return 0;
}