#include <iostream>
#include <string>
#include <map>
#include <vector>

class vertex;
class graph;

class graph {
public:
    typedef std::vector<vertex>			vertex_vector;
    typedef vertex_vector::size_type		vertex_id;
    typedef std::map<std::string, vertex_id>	vertex_index;

    vertex_vector V;
    vertex_index V_index;

    std::istream & read(std::istream & input);

private:
    size_t add_vertex(const std::string & name);
};

class vertex {
public:
    std::string name;
    std::vector<graph::vertex_id> adj;

    vertex(const std::string & n) : name(n) {};
};

size_t graph::add_vertex(const std::string & name) {
    std::pair<vertex_index::iterator, bool> 
	pib = V_index.insert(vertex_index::value_type(name, V.size()));
    if (pib.second) 
	V.push_back(vertex(name));
    return pib.first->second;
}

std::istream & graph::read(std::istream & input) {
    std::string u_name, v_name, edge;

    while (input >> u_name >> edge >> v_name) {
	size_t u = add_vertex(u_name);
	size_t v = add_vertex(v_name);

	if (edge == "--") {
	    V[u].adj.push_back(v);
	    V[v].adj.push_back(u);
	} else if (edge == "->") {
	    V[u].adj.push_back(v);
	} else if (edge == "<-") {
	    V[v].adj.push_back(u);
	}
    }
    return input;
}