#include <iostream>
#include <string>
#include <stack>
#include <fstream>
class text_buffer
{
  std::string m_text;
public:
  typedef std::string::const_iterator const_iterator;
  const_iterator begin() const  {return m_text.begin();}
  const_iterator end() const {return m_text.end();}
  
  bool read_from_file(const std::string & file_name)
  {
    m_text.clear();
    std::ifstream istr(file_name.c_str(),std::ios::binary);
    if(!istr)
      {
	std::cerr << "can't open input file:" << file_name << std::endl;
	return false;
      }
    int n = 0;
    char buf[1024];
    while(n = istr.readsome(buf,1024))
      m_text.append(buf,buf+n);
    return true;
  }
  
};


class validator
{
  std::string tgOpen;
  std::string tgClose;
public:
  bool  init(const std::string & tag_file)
  {
    std::ifstream istr(tag_file.c_str());
    if(!istr)
      {
	std::cerr << "can't open tag's file " << std::endl;
	return false;
      }
    std::getline(istr,tgOpen);
    std::getline(istr,tgClose);
    if(tgOpen.size() != tgClose.size())
      {
	std::cerr << "tag's file has incorrect format" << std::endl;
	return false;
      }
    return true;
  }

  void validate(const text_buffer & text)
  {
    bool comment = false;
    std::stack<char> tags;
    text_buffer::const_iterator cur = text.begin(), end = text.end();
    
    for (;cur != end;++cur) 
      {
	if (*cur == '!')
	  comment=!comment;
	
	if (!comment) 
	  {
	    if( tgOpen.find(*cur) != std::string::npos)
	      {
		std::cout << *cur << std::endl;
		tags.push(*cur);
		continue;
	      }
	    int n;
	    if( (n = tgClose.find(*cur)) != std::string::npos)
	      {
	      std::cout << *cur << std::endl;
	      if (!tags.empty()) 
		{
		  if (tgOpen[n] != tags.top())
		    std::cout<<"tags error 1!"<<std::endl;
		  tags.pop();
		} 
	      else 
		{
		  std::cout<<"tags error 2!"<<std::endl;
		}
	      }
	  }
      }
    if (!tags.empty()) 
      {
	std::cout<<"tags error 3!"<<std::endl;
      }
    std::cout<<"comment: "<<comment<<std::endl;
  }
  
};

int main(int argc, char ** argv)
{

  if(argc != 3)
    {
      std::cerr <<"Usage: validator <text_file> <tag_file>" << std::endl;
      return 1;
    }

  text_buffer text;
  if(!text.read_from_file(argv[1]))
    {
      return 1;
    }
  validator val;
  if(!val.init(argv[2]))
    {
      return 1;
    }
  val.validate(text);
  return 0;

}