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(){
  int n;
  int a[200000];
  int max,i,j,min;
  scanf("%d",&n);
  for(i=0; i<n; i++) scanf("%d",&a[i]);
  max=a[1]-a[0];
  min=a[0];
  for(i=1; i<n; i++){
    if(min>a[i]) min=a[i];
    else{
      a[i]-=min;
      if(a[i]>max) max=a[i];
    }
  }
  printf("%d\n",max);
  return 0;
}