(use gauche.sequence)(let[(o(make-list 57""))(i 0)](port-map(rec'l(dotimes(j(#0=size-of l))(set! #1=(ref o(-(+ 49 i)j))(format"~va~a"(+ i i j j)#1#(ref l j))))(inc! i))read-line)(map print(filter #/./o)))
Note that non-ascii characters in the above source code will be escaped (such as \x9f).