import Data.Functor
import Data.List
import Data.Maybe

main :: IO ()
main = do
  n <- readLn
  s <- getLine
  print $ solve n s

solve :: Int -> String -> Int
solve n s = fromMaybe n m
  where
    m = snd <$> find ((== "xx") . fst) (zip (zipWith (\a b -> [a, b]) s (tail s)) [1..])