e-olymp
Problems

Simple deque

Simple deque

Implement the "deque" data structure. Write a program that describes the deque and simulates its operations. You must implement all methods given below. The program reads the sequence of commands and executes the corresponding operation. After executing each command the program must print one line. The possible commands for the program are:

push_front

Add (put) into the front of the deque the new element. The program must print ok.

push_back

Add (put) into the end of the deque the new element. The program must printok.

pop_front

Pop the first element from the deque. The program must print its value.

pop_back

Pop the last element from the deque. The program must print its value.

front

Find the value of the first element (not deleting it). The program must print its value.

back

Find the value of the last element (not deleting it).The program must print its value

size

Print the number of elements in the deque.

clear

Clear the deque (delete all its elements) and print ok.

exit

The program must print bye and terminate.

It is guaranteed that the number of elements in the deque at any time does not exceed 100. All the operations:

  • pop_front,
  • pop_back,
  • front,
  • back

are usually correct.

Input

Given in the problem statement. Look at sample input.

Output

Given in the problem statement.Look at sample output.

Time limit 1 second
Memory limit 122.17 MiB
Input example #1
push_back 3
push_front 14
size
clear
push_front 1
back
push_back 2
front
pop_back
size
pop_front
size
exit
Output example #1
ok
ok
2
ok
ok
1
ok
1
2
1
1
0
bye

Example description: Количество элементов во всех структурах данных не превышает 10000, если это не указано особо.