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>
#include<math.h>

int main(){
	int n;
	int val[200000];
	int ret = -pow(10,9);
	int max = 0;
	int max_i = 0;
	scanf("%d",&n);
	for(int i = 0; i < n; i++){
		scanf("%d",&val[i]);
		if(max <= val[i]){
			max = val[i];
			max_i = i;
		}
	}
	for(int i = 0; i < n - 1; i++){
		if(max_i == i){
			max = 0;
			max_i = 0;
			for(int u = i + 1; u < n; u++){
				if(max <= val[u]){
					max = val[u];
					max_i = u;
				}
			}
		}
		if(ret < max - val[i]){
			ret = max - val[i];
		}
	}
	
	printf("%d\n",ret);
	return 0;
}