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>

int main(void){
   int n, i, j, m, x, y;

   scanf("%d", &n);

   int a[n];

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

   x = a[1] - a[0];
   y = a[0];

   for(j = 1; j < n; j++) {
      if (a[j - 1] < y){
         y = a[j - 1];
      }
      if (a[j] >= y){
         m = a[j] - y;
         if (x < m){
            x = m;
         }
      }
   }

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

   return 0;
}