/in/foo.cc: In function 'int maxy(int, int)':
/in/foo.cc:17:9: warning: 'maxy' may be used uninitialized in this function [-Wmaybe-uninitialized]
  return maxy;
         ^~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:37:19: warning: 'maxy' may be used uninitialized in this function [-Wmaybe-uninitialized]
  cout << maxy(a, b) << endl;
                   ^