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(void){
	int i,j,n;
	int rt[200000],maxmin;
	int maxv,minv;
	int min;
	scanf("%d",&n);
	scanf("%d",&rt[0]);
	scanf("%d",&rt[1]);
	minv=rt[0];
	maxv=rt[1]-rt[0];
	if(rt[1]<minv) minv=rt[1];
	for(i=2;i<n;i++){
		scanf("%d",&rt[i]);
		if(rt[i]-minv>maxv){
			maxv=rt[i]-minv;
		}
		if(rt[i]<minv){
			minv=rt[i];
		}
	}
	printf("%d\n",maxv);
	return 0;
}