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 = succ <$> elemIndex "xx" (zipWith (\a b -> [a, b]) s (tail s))