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++14 (judge verdict: Time Limit Exceeded)

#include <bits/stdc++.h>
using namespace std;
long long n,a[1000000],x,y,ma;
int main(){
	cin>>n;
	for(x=0;x<n;x++){
		cin>>a[x];
		for(y=x-1;y>=0;y--){
			if(x==1&&y==0){
			    ma=a[x]-a[y];
			}
		    if (ma<a[x]-a[y]){
				ma=a[x]-a[y];
		    }
	    }
	 }  
	cout<<ma<<endl;
}