/in/foo.cc: In function 'void test01(std::vector<int>&)':
/in/foo.cc:42:16: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   42 |   for(int i=0;i<s.size();i++)
      |               ~^~~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:151:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::vector<int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  151 |     for(int i=0;i<v.size();i++)
      |                 ~^~~~~~~~~
/in/foo.cc: In function 'std::vector<int> test04(int)':
/in/foo.cc:117:1: warning: control reaches end of non-void function [-Wreturn-type]
  117 | }
      | ^