{-# LANGUAGE OverloadedStrings #-}

import Data.ByteString.Char8 (ByteString)
import qualified Data.ByteString.Char8 as B

main :: IO ()
main = B.getLine >> solve <$> B.getLine >>= print

solve :: ByteString -> Int
solve = f 0
  where
    f ct s
      | B.null s = ct
      | "CPCTF" `B.isPrefixOf` s = f (ct + 1) (B.drop 5 s)
      | "CPCTCPC" `B.isPrefixOf` s = f (ct + 1) (B.drop 7 s)
      | otherwise = f ct (B.tail s)