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>

#define Num 200000
int main(void){

    int l, n, i, j, max, min;
    int a[Num];

    scanf("%d", &l); 

    for(i = 0; i <= l-1; i++){
        scanf("%d", &n); 
        a[i] = n;
    }

    max = a[1] - a[0];
    if(a[1] > a[0]){
        min = a[0];
    }else{
        min = a[1];
    }

    for (i = 2; i <= l-1; i++) {
        if (a[i] < min){
            min = a[i];
        }else if(max < a[i]-min) {
            max = a[i]-min;
        }
    }

    printf("%d\n", max);

    return 0;
}