/in/foo.cc: In function 'long long int Mul(long long int, long long int)':
/in/foo.cc:13:1: warning: no return statement in function returning non-void [-Wreturn-type]
 }
 ^
/in/foo.cc: In function 'std::__cxx11::string Add(std::__cxx11::string, std::__cxx11::string)':
/in/foo.cc:34:1: warning: no return statement in function returning non-void [-Wreturn-type]
 }
 ^