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>
#include <stdlib.h>


int main()
{
    int i;

    //??\???
    int n;
    scanf("%d", &n);
    int R[n];
    for( i = 0; i < n; ++i )
        scanf("%d", &R[i]);

    //min???????°???????????????????max????????¶
    int min = R[0], max = R[1] - R[0];
    for( i = 1; i < n; ++i ){
        max = max < R[i] - min ? R[i] - min : max;
        min = min > R[i] ? R[i] : min;
    }

    printf("%d\n", max);

    return 0;
}