/in/foo.cc: In member function 'BigInteger BigInteger::operator+(const BigInteger&) const':
/in/foo.cc:35:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
 if (g == 0 && i >= s.size() && i >= b.s.size()) break;
               ~~^~~~~~~~~~~
/in/foo.cc:35:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
 if (g == 0 && i >= s.size() && i >= b.s.size()) break;
                                ~~^~~~~~~~~~~~~
/in/foo.cc:37:7: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
 if (i < s.size()) x += s[i];
     ~~^~~~~~~~~~
/in/foo.cc:38:7: 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:48:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
 if (g == 0 && i >= s.size() && i >= b.s.size()) break;
               ~~^~~~~~~~~~~
/in/foo.cc:48:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
 if (g == 0 && i >= s.size() && i >= b.s.size()) break;
                                ~~^~~~~~~~~~~~~
/in/foo.cc:50:7: 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:60:10: 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:60:34: 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:62:16: 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:121:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
 for (int j = 0; j < strlen(buf); j++) out << buf[j];
                 ~~^~~~~~~~~~~~~