operations :: [String] -> Int
operations (s : t : _) = operations' 0 [s, t]
    where
        operations' n [[], []] = n
        operations' n [(s : ss), (t : ts)]
            | s == t    = operations' n [ss, ts]
            | otherwise = flip operations' [ss, ts] $ n + 1

main :: IO ()
main = getLine >> getContents >>= print . operations . lines