// mugs.cpp : This file contains the 'main' function. Program execution begins and ends there.
//

#include <iostream>
#include <vector>
#include <queue>

using namespace std;

int const bc = 't' - 'a' + 1;

struct Node
{
	Node* par_ = nullptr;
	Node* l_son_ = nullptr;
	Node* r_son_ = nullptr;

	vector<int> counts_;
	int subtr_s_;

	Node(Node* ls, Node* rs)
	{
		counts_.resize(bc);
		for (int i = 0; i < bc; i++)
		{
			counts_[i] = ls->counts_[i] + rs->counts_[i];
		}
		l_son_ = ls;
		r_son_ = rs;
		l_son_->par_ = this;
		r_son_->par_ = this;
		subtr_s_ = l_son_->subtr_s_ + r_son_->subtr_s_;
	}

	Node(int b)
	{
		counts_.resize(bc);
		counts_[b] = 1;
		subtr_s_ = 1;
	}
};

bool are_valid(Node* n1, Node* n2)
{

}

int main()
{
	int N;
	cin >> N;
	vector<int> D(N);
	char ch;
	queue<Node*>* nds = new queue<Node*>();
	for (int i = 0; i < N; i++)
	{
		cin >> ch;
		D[i] = ch - 'a';

		Node* nd = new Node(ch - 'a');
		nds->push(nd);
	}

	Node* root = nullptr;
	queue<Node*>* ndsn = new queue<Node*>();

	while (true)
	{
		while (nds->size() > 0)
		{
			Node* s1 = nds->front();
			nds->pop();
			Node* s2 = nullptr;
			if (nds->size() > 0)
			{
				s2 = nds->front();
				nds->pop();
			}

			Node* par = nullptr;
			if (s2 != nullptr)
				par = new Node(s1, s2);
			else
				par = s1;

			ndsn->push(par);
		}

		if (ndsn->size() == 1)
		{
			root = ndsn->front();
			break;
		}

		queue<Node*>* tmp = nds;
		nds = ndsn;
		ndsn = tmp;
	}

	int max_sz = 0;



	
}

// Run program: Ctrl + F5 or Debug > Start Without Debugging menu
// Debug program: F5 or Debug > Start Debugging menu

// Tips for Getting Started: 
//   1. Use the Solution Explorer window to add/manage files
//   2. Use the Team Explorer window to connect to source control
//   3. Use the Output window to see build output and other messages
//   4. Use the Error List window to view errors
//   5. Go to Project > Add New Item to create new code files, or Project > Add Existing Item to add existing code files to the project
//   6. In the future, to open this project again, go to File > Open > Project and select the .sln file