import Control.Applicative
import Control.Monad
import qualified Data.ByteString.Char8 as B
import Data.Maybe (fromJust)
import Text.Printf
import Debug.Trace

getInts :: IO [Int]
getInts = map (fst . fromJust . B.readInt) . B.words <$> B.getLine

substr :: Int -> Int -> B.ByteString -> B.ByteString
substr b l s = B.take l $ B.drop b s

main = do
  s <- B.getLine
  let b = fromJust $ 'A' `B.elemIndex` s
  let e = B.length s - (fromJust $ B.elemIndex 'Z' $ B.reverse s)
  print $ e-b
