/in/foo.cc: In function 'int main()':
/in/foo.cc:13:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   13 |         for(int i=0;i<=s.size();i++)
      |                     ~^~~~~~~~~~
/in/foo.cc:15:18: error: 'substr' was not declared in this scope; did you mean 'strstr'?
   15 |         string a=substr(0,wz);
      |                  ^~~~~~
      |                  strstr