vector<char> &int128_str(int128_t x) {
  vector<char> s;
  int  tail  = 0;
  int  count = 0;
  bool read  = true;

  __int128_t temp
  __int128_t test = 1;

  if (x < ((__int128_t)0))
    s.push_back('-'), x = - x;
  if (x == ((__int128_t)0)) {
    s.push_back('0');
	return s;
  }

  while((test <= x) && (read)) {
    test = test + test; if (test < ((s128_o) 0)) { read = false; } t = test;
    test = test + test; if (test < ((s128_o) 0)) { read = false; }
    test = test + test; if (test < ((s128_o) 0)) { read = false; }
    test = test + t;    if (test < ((s128_o) 0)) { read = false; }
    count ++;
  }
  while(count-- > 0) {
    test = tail = 1;
    for(int i = 0; i < count; i++) {
      test = test + test; t = test;
      test = test + test;
      test = test + test;
      test = test + t;
    }
    while(x >= test)
      x = x - test, tail++;
    s.push_back('0' + tail);
  }
  return s;
}