import Control.Monad
import Data.Char
import Data.List
    
f :: Char -> Int
f c
  | isAlpha c = ord c - ord 'A' + 10
  | otherwise = digitToInt c

main = do
  n <- readLn
  as <- replicateM n $ do
          s <- getLine
          let
              l = ['0'..'9'] ++ ['a'..'z']
              b = maximum $ map ((+1) . f) s
              g [] x = x
              g (c:s) x = g s (x * b + f c)
           in return $ g s 0
  print $ minimum as