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<math.h>
#include<time.h>
#include<string.h>
#include<stdlib.h>
#include<stdio.h>
int maxa(int x,int y)
{
	if(x>y)
		return x;
	return y;
}
int mina(int v,int u)
{
	if(v<u)
		return v;
	return u;
}
int main()
{
	int t,n,i,maxv=-2000000000,R[200010];
	scanf("%d",&n);
	for(i=1;i<=n;i++)
		scanf("%d",&R[i]);
	int minv=R[1];
	for(i=2;i<=n;i++)
	{
		maxv=maxa(maxv,R[i]-minv);
		minv=mina(minv,R[i]);
	}
	printf("%d\n",maxv);
	return 0;
}