
import qualified Data.Vector.Unboxed as U
import qualified Data.Vector as V
import qualified Data.ByteString.Char8 as C
import Debug.Trace
import Data.List
import Control.Monad
import Data.Ord
import qualified Data.Sequence as Seq

r :: Int -> IO (U.Vector Int)
r n = U.unfoldrN n (C.readInt . C.dropWhile (==' ')) <$> C.getLine

r' :: IO [Int]
r'  =   unfoldr    (C.readInt . C.dropWhile (==' ')) <$> C.getLine

rp :: IO (Int,Int)
rp  = toTup . unfoldr    (C.readInt . C.dropWhile (==' ')) <$> C.getLine

toTup [a,b] = (a,b)



main :: IO ()
main = do
    s <- getLine
    print $ cnt 0 0 s



cnt _ ac [] = ac
cnt 0 ac ('g':xs) = cnt 1 ac xs
cnt c ac ('g':xs) = cnt (c-1) (ac+1) xs
cnt 0 ac ('p':xs) = cnt 1 (ac-1) xs
cnt c ac ('p':xs) = cnt (c-1) ac xs



