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>

#define N 200000

int Calc_max_marge(int *,int);

int main(void){
  int A[N],num;
  int i;

  scanf(" %d",&num);
  for(i = 0; i < num; i++){
    scanf(" %d",&A[i]);
  }

  printf("%d\n",Calc_max_marge(A,num));
  
  return 0;
}

int Calc_max_marge(int *A,int num){
  int i;
  int min,max=A[1]-A[0];

  min = A[0];

  for(i = 1; i < num; i++){
    max = max > A[i]-min ? max : A[i]-min;
    min = min < A[i] ? min : A[i];
  }

  return max;
}