/in/foo.cc: In function 'bool judge(std::__cxx11::string, std::__cxx11::string, std::__cxx11::string)':
/in/foo.cc:9:30: error: 'reverse' was not declared in this scope
  reverse(s1.begin(), s1.end());
                              ^
/in/foo.cc: In function 'int main()':
/in/foo.cc:26:31: error: 'reverse' was not declared in this scope
   reverse(s1.begin(), s1.end()), cout << s1 << endl;
                               ^
/in/foo.cc:28:31: error: 'reverse' was not declared in this scope
   reverse(s2.begin(), s2.end()), cout << s2 << endl;
                               ^
/in/foo.cc:30:31: error: 'reverse' was not declared in this scope
   reverse(s3.begin(), s3.end()), cout << s3 << endl;
                               ^