module Main where

solve :: String -> Int -> Int
solve ss n =
    let
        l = length ss
        c = length $ filter (== 'a') ss
        (m, r) = n `divMod` l
        d = length $ filter (== 'a') $ take r ss
     in
        m * c + d

main :: IO ()
main = do
    ss <- getLine :: IO String
    n <- readLn :: IO Int
    print $ solve ss n