#include <sstream>
#include <iomanip>
template <class T>
inline std::string to_string (const T& t)
{
  std::stringstream ss;
  ss << t;
  return ss.str();
}
template <class T>
inline std::string to_string (const T& t,int w)
{
  std::stringstream ss;
  ss << std::setfill('0') << std::setw(w) << t;
  return ss.str();
}
template <class T>
inline T from_string (std::string t)
{
  std::stringstream ss;
  ss.str(t);
  T x;
  ss >> x;
  return x;
}