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>
int max(int a,int b){
	if(a>b){return a;}
	else{return b;}
}
main(){
	int i,r1,r2,cumDif,maxDif,tmpDif;
	scanf("%d %d %d",&i,&r1,&r2);
	cumDif=r2-r1;
	maxDif=cumDif;
	r1=r2;
	while(scanf("%d",&r2)!=EOF){
		tmpDif=r2-r1;
		cumDif=tmpDif+max(cumDif,0);
		if(maxDif<cumDif){maxDif=cumDif;}
		r1=r2;
	}
	if(maxDif<cumDif){maxDif=cumDif;}
	printf("%d\n",maxDif);
	return 0;
}