main = do
  _ <- getLine
  s <- getLine
  let ans = compute s
  print ans

type Animal = Char -- 'S' or 'W'
type OX     = Char -- 'o' or 'x'

next :: (Animal, Animal) -> OX -> (Animal, Animal)
next ( a, 'S') 'o' = ('S', a)
next ( a, 'W') 'x' = ('W', a)
next ('S', b )  _  = (b, 'W')
next ('W', b )  _  = (b, 'S')

compute s = if null answers then "-1" else head answers
  where
    answers =
      [ map fst (tail seq)
      | i <- [('S','S'),('S','W'),('W','S'),('W','W')]
      , let seq = scanl next i s
      , head seq == last seq
      ]
