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>
int max(int *,int);
int main(void){
        int arr[200000],i,j,num,temp,temp_1,max_ans,max_temp,temp_arr[200000],a[200000];
        scanf("%d",&num);
        for(i=0;i<num;i++) scanf("%d",&arr[i]);
        for(i=0;i<num;i++){
                for(j=0;j<i;j++){
                        //if(i==1) temp = arr[i] - arr[j];
		//	if(i==0)break;
                                temp_arr[j] = arr[i] - arr[j];
                                //max_temp=max(temp_arr,i);
				//a[i] = max_temp;
			}
		//if(i != 0){
			max_temp = max(temp_arr,i);
			a[i] = max_temp;
		//	}
		}
	//putchar('\n');
	max_ans = max(a,num);
	//putchar('\n');
	printf("%d\n",max_ans);
        return 0;
}
int max(int *arr, int num){
	int max=-2147483648,i;
	for(i=0;i<num;i++)if(max<arr[i]) max = arr[i];
	//printf("%d",max);
	return max;
}