/in/foo.cc: In function 'int main()':
/in/foo.cc:9:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
    9 |         for(int i=0;i<s.size();i++)
      |                     ~^~~~~~~~~
/in/foo.cc:15:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   15 |         for(int i=0;i<a.size();i++)
      |                     ~^~~~~~~~~
/in/foo.cc:16:30: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   16 |                 for(int j=0;j<b.size();j++)
      |                             ~^~~~~~~~~
/in/foo.cc:20:38: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   20 |                         for(int k=0;k<c.size();k++)
      |                                     ~^~~~~~~~~