/in/foo.cc: In function 'std::__cxx11::string yd(std::__cxx11::string, int)':
/in/foo.cc:34:23: warning: 'zy' may be used uninitialized in this function [-Wmaybe-uninitialized]
   a[zx][zy]=a[zx-1][zy];
             ~~~~~~~~~~^
/in/foo.cc:40:12: warning: 'zx' may be used uninitialized in this function [-Wmaybe-uninitialized]
   a[zx][zy]=a[zx+1][zy];
   ~~~~~~~~~^~~~~~~~~~~~