Problem:
MathJax.Hub.Config({ tex2jax: { inlineMath: [["$","$"], ["\\(","\\)"]], processEscapes: true }});

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(void)
{
    int n;
    static long r[200000];
    long maxv;
    long minv;
    
    scanf("%d", &n);
    
    for ( int i = 0; i < n; i++ ) {
        scanf("%ld", &r[i]);
    }
    
    maxv = r[1] - r[0];
    minv = r[0];
    
    for ( int j = 1; j < n; j++ ) {
        if ( r[j] - minv > maxv ) {
            maxv = r[j] - minv;
        }
        if ( r[j] < minv ) {
            minv = r[j];
        }
    }
    
    printf("%ld\n", maxv);
    
    return 0;
}