/in/foo.cc: In member function 'BIG BIG::operator+(const BIG&) const':
/in/foo.cc:49:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    if(count==0&&i>=s.size()&&i>=b.s.size()) break;
                 ~^~~~~~~~~~
/in/foo.cc:49:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    if(count==0&&i>=s.size()&&i>=b.s.size()) break;
                              ~^~~~~~~~~~~~
/in/foo.cc:51:8: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    if(i<s.size()) x+=s[i];
       ~^~~~~~~~~
/in/foo.cc:52:8: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    if(i<b.s.size()) x+=b.s[i];
       ~^~~~~~~~~~~
/in/foo.cc: In member function 'BIG BIG::operator*(int) const':
/in/foo.cc:62:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    if(carry==0&&i>=s.size()) break;
                 ~^~~~~~~~~~
/in/foo.cc: In member function 'bool node::operator<(const node&) const':
/in/foo.cc:100:9: error: could not convert 'std::operator+(const std::__cxx11::basic_string<_CharT, _Traits, _Alloc>&, const std::__cxx11::basic_string<_CharT, _Traits, _Alloc>&) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>](b.node::num)' from 'std::__cxx11::basic_string<char>' to 'bool'
   if(num+b.num) return true;
      ~~~^~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:11:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
 #define Rf(a,b,c) for(R int(a)=(b);(a)<=(c);++(a))
                                    ~~~^~~~~
/in/foo.cc:158:7: note: in expansion of macro 'Rf'
  else Rf(len,1,s.size()) {
       ^~