Design a FIFO (First In, First Out) Queue using only two Stacks.

The implemented MyQueue class should support the following standard queue operations:

push(x) → Adds an element x to the back of the queue.

size() → Returns the total number of elements currently in the queue.

pop() → Removes and returns the element from the front of the queue.

peek() → Returns the front element without removing it.

empty() → Returns true if the queue is empty, otherwise false.

Note:

Only standard stack operations are allowed: push to top, peek/pop from top, size, and empty.

If your language doesn't have a built-in stack, you can simulate one using a list or deque (double-ended queue), as long as you restrict yourself to standard stack behavior.

Example 1:

Input:
["MyQueue", "push", "push", "size", "peek", "pop", "empty", "pop", "empty"]
[[], [1], [5], [], [], [], [], [], []]

Output: [null, null, null, 2, 1, 1, false, 5, true]

Explanation:
1. MyQueue myQueue = new MyQueue(); → Initializes an empty queue.
2. myQueue.push(1); → Queue becomes [1].
3. myQueue.push(5); → Queue becomes [1, 5] (leftmost is front of the queue).
4. myQueue.size(); → Returns 2 (there are two elements in queue).
5. myQueue.peek(); → Returns 1 (the front element).
6. myQueue.pop(); → Removes and returns 1, queue becomes [5].
7. myQueue.empty(); → Returns false (queue is not empty).
8. myQueue.pop(); → Removes and returns 5, queue becomes [], empty.
9. myQueue.empty(); → Returns true (queue is empty).

Example 2:

Input: 
["MyQueue", "push", "push", "pop", "push", "peek", "size", "pop", "pop", "empty"]
[[], [10], [20], [], [30], [], [], [], [], []]

Output:[null, null, null, 10, null, 20, 2, 20, 30, true]

Explanation:
1. MyQueue myQueue = new MyQueue(); → Initializes an empty queue.
2. myQueue.push(10); → Queue becomes [10].
3. myQueue.push(20); → Queue becomes [10, 20].
4. myQueue.pop(); → Removes and returns 10, queue becomes [20].
5. myQueue.push(30); → Queue becomes [20, 30].
6. myQueue.peek(); → Returns 20, the front element.
7. myQueue.size(); → Returns 2.
8. myQueue.pop(); → Removes and returns 20, queue becomes [30].
9. myQueue.pop(); → Removes and returns 30, queue becomes [].
10. myQueue.empty(); → Returns true.

Example 3:

Input:
["MyQueue", "push", "push", "push", "peek", "peek", "pop", "size", "pop", "peek", "empty"]
[[], [2], [4], [6], [], [], [], [], [], [], []]

Output: [null, null, null, null, 2, 2, 2, 2, 4, 6, false]

Explanation:
1. MyQueue myQueue = new MyQueue(); → Initializes an empty queue.
2. myQueue.push(2); → Queue becomes [2].
3. myQueue.push(4); → Queue becomes [2, 4].
4. myQueue.push(6); → Queue becomes [2, 4, 6].
5. myQueue.peek(); → Returns 2, but does not remove it.
6. myQueue.peek(); → Returns 2 again.
7. myQueue.pop(); → Removes and returns 2, queue becomes [4, 6].
8. myQueue.size(); → Returns 2.
9. myQueue.pop(); → Removes and returns 4, queue becomes [6].
10. myQueue.peek(); → Returns 6.
11. myQueue.empty(); → Returns false.

Constraints

1 <= x <= 9

At most 100 calls will be made to push, size, pop, peek, and empty.

All the calls to pop and peek are valid.

60. Implement Queue using Two Stacks