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 <math.h>

#define MAX 200000
#define INF 1e9

int main(){
  int N,a[MAX],mini[MAX],i,ans;

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

  mini[0] = a[0];
  ans = -INF;
  for(i = 1 ; i < N ; i++){
    ans = fmax(ans,a[i]-mini[i-1]);
    mini[i] = fmin(a[i],mini[i-1]);
  }
  printf("%d\n" ,ans);

  return 0;
}