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 <limits.h>
#define N 200001
#define imax(a,b) (a>b)?a:b
#define imin(a,b) (a<b)?a:b

int main()
{
  int n,r;
  scanf("%d",&n);
  int ans=INT_MIN,rmin;
  
  int i;
  for(i=0;i<n;i++){
    scanf("%d",&r);
    if(i==0) rmin=r;
    else{
      ans=imax(ans,r-rmin);
      rmin=imin(r,rmin);
    }
  }
  
  printf("%d\n",ans);
  return 0;
}