/in/foo.cc: In function 'int mex(std::vector<int>&)':
/in/foo.cc:21:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i < array.size(); i++)
                     ~~^~~~~~~~~~~~~~
/in/foo.cc:26:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^