/in/foo.cc: In function 'int main()':
/in/foo.cc:45:32: warning: 'y' may be used uninitialized in this function [-Wmaybe-uninitialized]
         planet[x-1][y] -= check( planet[x-2][y] );
                           ~~~~~^~~~~~~~~~~~~~~~~~
/in/foo.cc:45:42: warning: 'x' may be used uninitialized in this function [-Wmaybe-uninitialized]
         planet[x-1][y] -= check( planet[x-2][y] );
                                         ~^~