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>
int main(){
	int i, j, x,y;
	int n, *Rt;
	
	scanf("%d",&n);
	Rt = (int *)malloc(sizeof(int) * n);
	for(i=0; i<n; i++){
		scanf("%d",&Rt[i]);
	}
	
	x = Rt[1] - Rt[0];
	
	for(j=1; j<n; j++){
		for(i=j-1; i>=0; i--){
			y=Rt[j] - Rt[i];
			if(x<y){
				x = Rt[j] - Rt[i];
			}
		}
	}
	
	printf("%d\n",x);
	
	return 0;
}