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()
{
    long long int r[200001]={0}, i, j, n, max=-1000000000, c;
    scanf("%lld", &n);
    for(i = 0; i < n; i++){
        scanf("%lld", &r[i]);
    }
    for(i = 0; i < n; i++){
        while(1){
            if(i != 0 && r[i-1] < r[i] && i != (n - 1)){
                i++;
            } else {
                break;
            }
        }
        for(j = i + 1; j < n; j++){
            c = r[j] - r[i];
            if(c > max){
                max = c;
            }
        }
    }
    printf("%lld\n", max);
    return 0;
}