/in/foo.cc: In function 'std::__cxx11::string PalindromicString(std::__cxx11::string)':
/in/foo.cc:11:21: error: 'ceil' was not declared in this scope
      half=ceil(len/2);
                     ^
/in/foo.cc:10:5: warning: this 'else' clause does not guard... [-Wmisleading-indentation]
     else
     ^~~~
/in/foo.cc:12:2: note: ...this statement, but the latter is misleadingly indented as if it is guarded by the 'else'
  for(int i=1;i<=half;i++){
  ^~~