/in/foo.cc: In member function 'BigInteger BigInteger::operator+(const BigInteger&) const':
/in/foo.cc:43:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             if (g == 0 && i >= s.size() && i >= b.s.size()) break;
                           ~~^~~~~~~~~~~
/in/foo.cc:43:46: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             if (g == 0 && i >= s.size() && i >= b.s.size()) break;
                                            ~~^~~~~~~~~~~~~
/in/foo.cc:45:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             if (i < s.size()) x += s[i];
                 ~~^~~~~~~~~~
/in/foo.cc:46:19: 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 'BigInteger BigInteger::operator-(const BigInteger&) const':
/in/foo.cc:56:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             if (g == 0 && i >= s.size() && i >= b.s.size()) break;
                           ~~^~~~~~~~~~~
/in/foo.cc:56:46: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             if (g == 0 && i >= s.size() && i >= b.s.size()) break;
                                            ~~^~~~~~~~~~~~~
/in/foo.cc:58:19: 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 'BigInteger BigInteger::operator*(const BigInteger&) const':
/in/foo.cc:68:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for(i=0;i<s.size();i++) for(j=0;j<b.s.size();j++) v[i+j]+=LL(s[i])*b.s[j];
                 ~^~~~~~~~~
/in/foo.cc:68:42: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for(i=0;i<s.size();i++) for(j=0;j<b.s.size();j++) v[i+j]+=LL(s[i])*b.s[j];
                                         ~^~~~~~~~~~~
/in/foo.cc:70:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             if (g ==0 && i >= v.size()) break;
                          ~~^~~~~~~~~~~
/in/foo.cc: In function 'std::ostream& operator<<(std::ostream&, const BigInteger&)':
/in/foo.cc:130:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for (int j = 0; j < strlen(buf); j++) out << buf[j];
                         ~~^~~~~~~~~~~~~