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: Wrong Answer)

#include <stdio.h>

int main(int argc, const char * argv[]) {
    long n;
    long num[20001];
    int i, j;
    long max;
    
    scanf("%ld", &n);
    for (i=0; i<n; i++) {
        scanf("%ld", &num[i]);
    }
    max = num[1] - num[0];
    
    for (i=0; i<n; i++) {
        for (j=i+1; j<n; j++) {
            if (num[j] - num[i] > max) {
                max = num[j] - num[i];
            }
        }
    }
    
    printf("%ld\n", max);
    
    return 0;
}