/in/foo.cc: In function 'int onu(std::__cxx11::string, std::__cxx11::string, std::__cxx11::string)':
/in/foo.cc:7:21: warning: left operand of comma operator has no effect [-Wunused-value]
  for(int i=0,j=n-1;i<n,j>=0;i++,j--)
                    ~^~