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>
#include <string.h>
#include <math.h>
int main()
{
    long long max,min,a;
    int i,j,k;
    int tmp;
    int n;
    int m;

    scanf("%d",&n);

    scanf("%llu",&a);
    min = a;

    scanf("%llu",&a);
    max = a - min;
    if (min > a)
        min = a;

    for (i = 2; i < n; i++) {
        scanf("%lld",&a);
        if ( a-min > max)
            max = a-min;
        if (a < min)
            min = a;
    }

    printf("%lld\n",max);
    return 0;
}