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 a, b, c, n, i, m, p, cur;
    scanf("%d", &n);
    scanf("%d", &m);
    scanf("%d", &p);
    a=p-m;
    if(m>p){
        m=p;
    }   
    for (i = 2; i < n; i++){
        scanf("%d", &cur);
        b = cur-p;
        c = cur-m;
        if(b>c){
            if(a<b)a=b;
        }else if(a<c){
            a=c;
        }
        if(m>cur){
            m=cur;
        }
        p=cur;
    }
    printf("%d\n", a);
    return 0;
}