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 <stdlib.h>
int main(){
	int b,n,i,j,min=2147483647,max,ans=-214783648;
	int *r;
	scanf("%d",&n);
	r = malloc(sizeof(int) * (n));
	scanf("%d",r);
	max = min = *r;
	for(i=1; i<n; i++){
		scanf("%d",(r+i));
		max = *(r+i);
		//if(min != max)b = max - min;
		b = max - min;
		if(min > *(r+i))min = *(r+i);
		if(n==2 || ans < b)ans = b;
	}
	
	printf("%d\n",ans);
	free(r);
	return 0;
}