/in/foo.cc: In member function 'BigInt BigInt::operator+(const BigInt&) const':
/in/foo.cc:29:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             if (count == 0 && i >= s.size() && i >= b.s.size()) break;
                               ~~^~~~~~~~~~~
/in/foo.cc:29:50: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             if (count == 0 && i >= s.size() && i >= b.s.size()) break;
                                                ~~^~~~~~~~~~~~~
/in/foo.cc:31:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             if (i < s.size()) x += s[i];
                 ~~^~~~~~~~~~
/in/foo.cc:32:19: 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 'BigInt BigInt::operator-(const BigInt&) const':
/in/foo.cc:45:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             if (carry == 0 && i >= s.size() && i >= b.s.size()) break;
                               ~~^~~~~~~~~~~
/in/foo.cc:45:50: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             if (carry == 0 && i >= s.size() && i >= b.s.size()) break;
                                                ~~^~~~~~~~~~~~~
/in/foo.cc:48:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             if (i < s.size()) x += s[i]; else break;
                 ~~^~~~~~~~~~
/in/foo.cc:49:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             if (i < b.s.size()) x -= b.s[i];
                 ~~^~~~~~~~~~~~
/in/foo.cc: In function 'std::ostream& operator<<(std::ostream&, const BigInt&)':
/in/foo.cc:66:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             for(int j = 0; j < strlen(buf); j++) out << buf[j];
                            ~~^~~~~~~~~~~~~