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 <limits.h>

int main(void){
    int num;
    int maxValue;
    int minValue;
    int i;
    int r;

    maxValue = INT_MIN;
    minValue = INT_MAX;

    scanf( "%d" , &num );
    scanf( "%d" , &minValue );

    for ( i = 0 ; i < ( num - 1 ) ; i++ ){
        scanf( "%d" , &r );
        if ( maxValue < r - minValue ) {
            maxValue = r - minValue;
        }
        if ( minValue > r ) {
            minValue = r ;
        }
    }

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

    return 0;
}