Problem H

USING: io kernel math math.parser strings sequences locals ascii ;

IN: template

:: test ( rtn cur -- a b )

  cur "" =
  [ rtn cur ]
  [
    cur 1 tail
    cur 1 head

    rtn length 2 mod 0 =
    [ >upper rtn swap append ]
    [ >lower rtn swap append ]
    if

    swap
    test

  ]
  if ;



""
readln
test

drop
print