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<iostream>
#include<string>

using namespace std;
int main(){
	int n,a[200000],i,j,max,min_i;
	cin>>n;
	for(i=0;i<n;i++)
		cin>>a[i];
	min_i = a[0];
	max = a[1] - min_i;
	for(j=1;j<n;j++){
		max = (a[j] - min_i)>max? (a[j]-min_i) : max;
		min_i = a[j]<min_i?a[j]:min_i;
	}
	 cout<<max<<endl;
}