/in/foo.cc: In function 'int main()':
/in/foo.cc:89:20: warning: ISO C++ forbids converting a string constant to 'char*' [-Wwrite-strings]
     BigNum v("1234"), b("1321");
                    ^
/in/foo.cc:89:31: warning: ISO C++ forbids converting a string constant to 'char*' [-Wwrite-strings]
     BigNum v("1234"), b("1321");
                               ^