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: Time Limit Exceeded)

#include<stdio.h>
int main()
{
    int n,max,i,j,k,m;
    while(~scanf("%d",&n))
    {
    	int a[200000]={0};
        for(i=0;i<n;i++)
            scanf("%d",&a[i]);
        for(k=0;k<n-1;k++)
        {
        	if(a[k]<a[k+1])
        	{
        		break;
			}
		}
		if(k<n-1)
        max=a[k+1]-a[k];
        else
        {
        	k=0;
        	max=a[1]-a[0];
		}
        for(i=k;i<n-1;i++)
            for(j=i+1;j<n;j++)
            if(max<a[j]-a[i])
            max=a[j]-a[i];
        printf("%d\n",max);
    }
    return 0;
}