#include <iostream>
#include <queue>

using namespace std;

class Node
{
public :
	int Data;
	Node* Left;
	Node* Right;
	
	Node(int d) { Left=Right=NULL; Data = d; }
};

class Tree
{
private : 
	Node* Head;
	queue<Node*> q;
	bool flag;

	void Rec_Inorder(Node* h)
	{
		if (h==NULL) return;
		Rec_Inorder(h->Left);
		cout<<h->Data<<"  ";
		Rec_Inorder(h->Right);
	}
	
public : 
	Tree() { Head=NULL ; flag = false; }

	bool Add(int d)
	{
		Node* t = new Node(d);
		
		if (Head == NULL)
		{
			Head = t;
		}
		else
		{
			if (q.size() == 0) return false;			// age tu saf chizi nabashe dige nemitunim be derakht chizi ezafe konim
		
			Node* p = q.front();
			
			if (p->Left==NULL && flag==false)
			{
				p->Left = t;
			}
			else
			{
				p->Right = t;
				q.pop();
			}
		}
		
		q.push(t);
		flag = false;
		
		return true;
	}
	
	bool Ignore()
	{
		if (q.size() == 0) return false;
		
		Node* p = q.front();
		if (p->Left == NULL && flag == false)				/// --------------------------------------------------------- !!!
			flag = true;
		else
		{
			flag = false;
			q.pop();
		}
		
		return true;
	}
	
	void Inorder()
	{
		cout<<"Inorder = ";
		Rec_Inorder(Head);			// tu ghesmate private ha neveshte shode (Baaala)
		cout<<"\n";
	}
	
};

int main()
{
	Tree t;
	t.Add(15);
	t.Add(13);
	t.Ignore();
	t.Ignore();
	t.Add(4);
	t.Add(8);
	t.Add(7);

	t.Inorder();
	
	return 0;
}