/in/foo.cc: In member function 'UnsignedDigit UnsignedDigit::move(int) const':
/in/foo.cc:230:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         if (-k >= digits.size())
             ~~~^~~~~~~~~~~~~~~~
/in/foo.cc: In member function 'UnsignedDigit UnsignedDigit::operator*(const UnsignedDigit&) const':
/in/foo.cc:297:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i + 1 < tmp.size(); ++i) {
                     ~~~~~~^~~~~~~~~~~~