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()
{
    int m;
    while(scanf("%d",&m)!=EOF)
    {
        int i,max,min,n,x,b,a=0;
        for(i=0; i<m; i++)
        {
            scanf("%d",&n);
            if(i==0)
                min=n;
            if(i>a)
                x=n-min;
            if(min>n)
            {
                min=n;
                a=i;
            }
            if(i==1)
                b=x;
            if(i>1)
                if(b<x)
                    b=x;
        }
        printf("%d\n",b);
    }
}