#include <iostream>
#include <fstream>
#include <sstream>
#include <unordered_map>
#include <vector>

#include "util.h"

using Moves = std::vector<bool>;
using Map = std::unordered_map<int,std::pair<int,int>>;

constexpr char EQUAL[] = "=";

int encode(std::string str)
{
    int res{};
    for (unsigned char c : str)
    {
        if ('A' <= c and c <= 'Z')
        {
            res *= 1 + 'Z' - 'A';
            res += c - 'A';
        }
    }
    return res;
}

std::pair<Moves,Map> parse(const char* path)
{
    Map map{};
    Moves moves{};

    std::ifstream input{ path };
    if (input.is_open())
    {
        std::string line;
        std::getline(input,line);

        moves.resize(line.size());
        std::transform(line.cbegin(), line.cend(),
            moves.begin(), [](unsigned char c) { return c == 'L'; });

        std::string from, tol, tor;
        while (not std::getline(input,line).eof())
        {
            if (line.empty()) continue;

            std::istringstream in{ line };
            in >> from >> util::skip<EQUAL> >> tol >> tor;
            map.insert({ encode(from), { encode(tol), encode(tor) } });
        }
    }
    input.close();

    return { std::move(moves), std::move(map) };
}

int main(int argc, char* argv[])
{
    int answer{};

    auto [moves, map] = parse(argv[1]);

    for (int pos = encode("AAA");
         pos != encode("ZZZ");
         pos = moves[answer++ % moves.size()] ? map[pos].first : map[pos].second);

    std::cout << answer << std::endl;
    return 0;
}