Problem:
MathJax.Hub.Config({ tex2jax: { inlineMath: [["$","$"], ["\\(","\\)"]], processEscapes: true }});

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: Time Limit Exceeded)

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

int max(int,int);

int main(int argc, char** argv) {
    int size;
    scanf("%d\n", &size);
    if(size < 2 || size > 200000)
        return (EXIT_FAILURE);
    int array[size];
    
    for(int i = 0; i < size; i++){
        scanf("%u", &array[i]);
        if(array[i]<1 || size > 100000000)
            return(EXIT_FAILURE);
    }
    
    int maxVal = array[size - 1] - array[0];
    
    for(int j = size - 1; j >= 1; j--)
        for(int i = j - 1; i >= 0; i--){
            maxVal = max(maxVal, array[j] - array[i]);
            if(array[i] > array[j])
                j = i;
        }
    
    printf("%d\n", maxVal);
    
    return (EXIT_SUCCESS);
}

int max(int a, int b){
    if(a > b)
        return a;
    return b;
}