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 i,n;
	scanf("%d",&n);
	int r[n],minv[n],maxv[n],Max=-1000000000;
	for(i=0;i<n;i++){
		scanf("%d",&r[i]);
    }

	minv[0]=r[0];
	maxv[0]=r[n-1];
	for(i=1;i<n-1;i++){
		minv[i] = r[i]<minv[i-1]?r[i]:minv[i-1];
		maxv[i] = r[n-1-i]>maxv[i-1]?r[n-1-i]:maxv[i-1];
	}
	for(i=0;i<n-1;i++){
		Max = maxv[n-2-i]-minv[i]>Max?maxv[n-2-i]-minv[i]:Max;
	}
	printf("%d\n", Max);

	return 0;
}