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>

int main(void){
    int n, c[200000];
    int i, j;
    int sub, maxv, minv;
    scanf("%d", &n);
    for (i=0; i <= n; i++){
        scanf("%d", &c[i]);
    } 
    
    maxv = 1 - 1000000000; //10^9
    minv = c[0];
    
    /*
    for (j=1; j <= n-1; j++){
        for (i=0; i <= j-1; i++){
            sub = c[j] - c[i];
            if (sub > maxv){
                maxv = sub;
            }
        }
    }
    */
    for (j=1; j <= n-1; j++){
        sub = c[j] - minv;
        if (maxv < sub){
            maxv = sub;
        }
        if (minv > c[j]){
            minv = c[j];
        }
    }
    
    printf("%d\n", maxv);
    return 0;
}