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>

#define MAX(x, y) ((x)>=(y) ? (x):(y))
#define MIN(x, y) ((x)<=(y) ? (x):(y))

int main(int argc, char **argv) {
    int n;
    scanf("%d", &n);
    int ans = -1 << 30;
    int minr;
    scanf("%d", &minr);
    for(int i = 1; i < n; ++i) {
        int r;
        scanf("%d", &r);
        ans = MAX(ans, r - minr);
        minr = MIN(minr, r);
    }
    printf("%d\n", ans);
    return 0;
}