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)

/*
 * FileName:     maximum_profit_fix_2
 * CreatedDate:  2020-07-14 00:06:00 +0900
 * LastModified: 2020-07-14 00:15:48 +0900
 */

#include <stdio.h>
#include <stdlib.h>

int main(void){
    int n;scanf("%d", &n);
    long int *r = malloc(n*sizeof(long int));
    for(int i=0; i<n; i++)scanf("%ld", r+i);
    long int minv = r[0];
    long int maxv = -1000000000;
    long int ans = maxv-minv;
    for(int i=1; i<n; i++){
        maxv = r[i];
        if(maxv-minv>ans){
            ans = maxv - minv;
        }
        if(minv > r[i]){
            minv = r[i];
        }
    }
    printf("%ld\n", ans);
    free(r);
    return 0;
}