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: Time Limit Exceeded)

#include<stdio.h>
#include<stdlib.h>
#include<math.h>
#define N 13
#define pi M_PI

int main(){
    int n;
    scanf("%d",&n);
    int a[200000];
long max;
    for(int i=0;i<n;i++){
        scanf("%d",&a[i]);
    }
    max=-1000000000;
    for(int i=0;i<n-1;i++){
        for(int j=i+1;j<n;j++){
            long tmp = a[j]-a[i];
            if(max<tmp){
                max=tmp;
            }
        }
    }
    printf("%d\n",max);
   return 0;
}