@a=A..Z;eval'push@b,join"",@a;$|--?(@a[$-,$c]=@a[$c=$#a-$-,$-],$-++):splice@a,$-,0,splice@a,$#a-$-,1;'x25;splice@b,$_,1for 3,17;print$_,$/for@b,reverse@b[0..@b-2]
Note that non-ascii characters in the above source code will be escaped (such as \x9f).