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: Wrong Answer)

#include<stdio.h>

int main(void)
{
	int n,r[20001],i,j,a;
	int max=-1000000000,max1=-1000000000;
	
	scanf("%d",&n);
	for(i=0;i<n;i++){
		scanf("%d",&r[i]);
	}
	
	for(i=0;i<n-1;i++){
		for(j=i+1;j<n;j++){
			a=r[j]-r[i];
			if(max1<a){
				max1=a;
			}
		}
		if(max<max1){
			max=max1;
		}
	}
	
	printf("%d\n",max);
	return 0;
}