Implement the following operations of a queue using stacks.

• push(x) -- Push element x to the back of queue.
• pop() -- Removes the element from in front of queue.
• peek() -- Get the front element.
• empty() -- Return whether the queue is empty.

• You must use only standard operations of a stack -- which means only push to top
  , peek/pop from top, size, and is empty operations are valid.
• Depending on your language, stack may not be supported natively. You may simulate a stack by using a list or deque (double-ended queue), as long as you use only standard operations of a stack.

• You may assume that all operations are valid (for example, no pop or peek operations will be called on an empty queue).

  class MyQueue {
  public:
      /** Initialize your data structure here. */
      MyQueue() {
          
      }
      
      /** Push element x to the back of queue. */
      void push(int x) {
          while(!st1.empty())
          {
              st2.push(st1.top());
              st1.pop();
          }
          st1.push(x);
          while(!st2.empty())
          {
              st1.push(st2.top());
              st2.pop();
          }
      }
      
      /** Removes the element from in front of queue and returns that element. */
      int pop() {
        int top=st1.top();
        st1.pop();
        return top;
      }
      
      /** Get the front element. */
      int peek() {
          return st1.top();;
      }
      
      /** Returns whether the queue is empty. */
      bool empty() {
          return st1.empty();
      }
  private:
      stack<int> st1;
      stack<int> st2;
  };
  
  /**
   * Your MyQueue object will be instantiated and called as such:
   * MyQueue obj = new MyQueue();
   * obj.push(x);
   * int param_2 = obj.pop();
   * int param_3 = obj.peek();
   * bool param_4 = obj.empty();
   */