/in/foo.cc: In function 'int main()':
/in/foo.cc:103:8: warning: 'y1' may be used uninitialized in this function [-Wmaybe-uninitialized]
   ky[i]=y1;
   ~~~~~^~~
/in/foo.cc:104:14: warning: 'x1' may be used uninitialized in this function [-Wmaybe-uninitialized]
   vis[x1][y1]=true;
   ~~~~~~~~~~~^~~~~
/in/foo.cc:80:16: warning: 'yy' may be used uninitialized in this function [-Wmaybe-uninitialized]
     vis[xx][yy]=true;
     ~~~~~~~~~~~^~~~~
/in/foo.cc:80:16: warning: 'xx' may be used uninitialized in this function [-Wmaybe-uninitialized]