toStrList x = map return x::[String]
fil x = filter (\t -> t == "C" || t == "F") x
--check x = if x == "CF" then "Yes" else "No"
check :: String -> String
check str = if(take 2 str  == "CF")then  "Yes" else if length(str) == 1 then "No" else check (drop 1 str)
main ::IO()
main = do
        n <- getLine
        --print (toStrList n)
        putStrLn ((check.concat.fil.toStrList) n)
