/in/foo.cc: In function 'void setinter(std::vector<int>&, std::vector<int>&, std::vector<int>&)':
/in/foo.cc:6:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i < a1.size(); i++)
                     ~~^~~~~~~~~~~
/in/foo.cc:8:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for (int j = 0; j < a2.size(); j++)
                         ~~^~~~~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:69:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i < a4.size(); i++)
                     ~~^~~~~~~~~~~
/in/foo.cc:74:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i < a5.size(); i++)
                     ~~^~~~~~~~~~~