#include<iostream>
#include <stack>

#include <string>
#include <vector>

std::stack<int> input(std::string x)
{

	std::stack <int> in;

	for(int i = 0; i < x.length();)
	{

		if (x[i] == ' ') {
			i++; continue;
		}
		

		int k = x[i] - 48; i++;

		while (x[i] != ' ' && i != x.length())
		{
			k = k * 10 + x[i] - 48;

			i++;
		}

		in.push(k);

	}

	return in;

}

int main()
{
	
	std::string x, y;

	std::getline(std::cin, x);
	std::getline(std::cin, y);

	std::stack<int> a = input(x), b = input(y);

	int k = 0; std::vector<int> sort;

	int const total = a.size() + b.size();

	while (k != total)
	{
		
		if (a.top() > b.top())
		{
			std::cout << 'B';
			sort.push_back(b.top());
			if (b.size() != 1)
			{
				b.pop();
			}
			else {
				std::cout << 'A';
				sort.push_back(a.top()); k++;
			}
			
		}
		else {
			std::cout << 'A';

			sort.push_back(a.top());
			if (a.size() != 1)
			{
				a.pop();
			}
			else {
				std::cout << 'B'; k++;
				 sort.push_back(b.top());
			}
		}

		k++;
	}

	std::cout << std::endl;

	for (auto x : sort)
	{
		std::cout << x << " ";
	} 

}