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 main(){
    int i,j,n,Max,key,key2,count=1;
    int A[200001];
       
    scanf("%d",&n);
    for(i=1;i<=n;i++){
        scanf("%d",&A[i]);
    }
     
   Max=A[2]-A[1];
 key2=A[n];
for(i=n;i>=2;i--){
	if(count==1){
		if(key2<=A[i]){
	for(j=i,count=1;j>1;j--){
  if(count==1){
 if(Max<A[i]-A[j-1]){
           Max=A[i]-A[j-1];
			key=A[j-1];}
			 count++;}
             
		else if(count==2){
    if(key>A[j-1]){
	if(Max<A[i]-A[j-1]){
 	Max=A[i]-A[j-1];
	key=A[j-1];}}

    	key2=A[i];
    }
           count=1;  
             
}
		}}}
         
            printf("%d\n",Max);
            return 0;
        }