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 main()
{
  int i, num, maxnum, minnum, array[N];

  scanf("%d", &num);

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

  maxnum = array[1] - array[0];
  minnum = array[0];
  
  for( i=1; i<num; i++){
    if( maxnum <= ( array[i] - minnum ) ){
      maxnum = array[i] - minnum;
    }

    if( minnum >= array[i] ){
      minnum = array[i];
    }
  }

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

  return 0;
}