Problem:
Deque

For a dynamic array $A = \{a_0, a_1, ...\}$ of integers, perform a sequence of the following operations:

push($d$, $x$): Add element $x$ at the begining of $A$, if $d = 0$. Add element $x$ at the end of $A$, if $d = 1$.

randomAccess($p$): Print element $a_p$.

pop($d$): Delete the first element of $A$, if $d = 0$. Delete the last element of $A$, if $d = 1$.

$A$ is a 0-origin array and it is empty in the initial state.

Input

The input is given in the following format.

$q$
$query_1$
$query_2$
:
$query_q$

Each query $query_i$ is given by

0 $d$ $x$

or

1 $p$

or

2 $d$

where the first digits 0, 1 and 2 represent push, randomAccess and pop operations respectively.

randomAccess and pop operations will not be given for an empty array.

Output

For each randomAccess, print $a_p$ in a line.

Constraints

$1 \leq q \leq 400,000$

$0 \leq p < $ the size of $A$

$-1,000,000,000 \leq x \leq 1,000,000,000$

Sample Input 1

11
0 0 1
0 0 2
0 1 3
1 0
1 1
1 2
2 0
2 1
0 0 4
1 0
1 1

Sample Output 1

2
1
3
4
1

Solution in JAVA (judge verdict: Accepted)

import java.util.*;
import java.io.*;

public class Main {

	public static void main(String[] args) {
		Scanner in=new Scanner(System.in);
		PrintWriter out=new PrintWriter(System.out);
		//List<Integer> DQ=new ArrayList<>();
		MyDQ DQ=new MyDQ();
		int q=in.nextInt();
		
		for(int i=0;i<q;i++) {
			int query=Integer.parseInt(in.next());
			
			switch(query) {
			case 0:
				int d=Integer.parseInt(in.next()),x=Integer.parseInt(in.next());
				DQ.push(d, x);
				break;
				
			case 1:
				int p=Integer.parseInt(in.next());
				out.println(DQ.get(p));
				break;
				
			case 2:
				int e=Integer.parseInt(in.next());
				DQ.pop(e);
				break;
			}
		}
		out.flush();
	}

}

class MyDQ{
	int DQ[];
	int size,top,btm;
	
	MyDQ(){
		DQ=new int[1000000];
		size=0;
		top=500000; btm=499999;
	}
	
	void push(int d,int x) {
		if(d==0) {
			top--;
			DQ[top]=x;
		}
		else {
			btm++;
			DQ[btm]=x;
		}
		size++;
	}
	
	void pop(int d) {
		if(d==0) top++;
		else btm--;
		size--;
	}
	
	int get(int i) {
		return DQ[top+i];
	}
}