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>
#define nMIN 2
#define nMAX 200000
#define RtMIN 1
#define RtMAX 1000000000


int main(){
int R[nMAX],Time,i,max=0,sub;

scanf("%d",&Time);
if(nMIN<=Time&&Time<=nMAX){
for(i=0;i<Time;i++){
scanf("%d",&R[i]);
if(RtMIN>R[i]||R[i]>RtMAX)exit(1);
}
max=R[i-1];
sub=R[i-1]-R[i-2];
for(i=Time-2;i>=0;i--){

if(max<R[i]&&i!=0){
max=R[i];
}
if(sub<max-R[i]&&R[i]!=max){
sub=max-R[i];
}
}
}
 else exit(1);

printf("%d\n",sub);
return 0;
}