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,j,n;
  int data[N];
  int res,max_i;

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

  max_i=1;
  for(i=2;i<n;i++){
    if(data[max_i]<data[i]){
      max_i=i;
    }
  }
  res=data[1]-data[0];
  for(i=0;i<n-1;i++){
    if(max_i==i){
      max_i++;
      for(j=i+1;j<n;j++){
	if(data[max_i]<data[j]){
	  max_i=j;
	}
      }
      if(res<data[max_i]-data[i]){
	res=data[max_i]-data[i];
      }
    }
    else{ 
      if(res<data[max_i]-data[i]){
	res=data[max_i]-data[i];
      }
    }
  }
  printf("%d\n",res);
  return 0;
}