import Data.Char

main :: IO ()
main = do
  l1 <- getLine
  l2 <- getLine
  let n = read l1 :: Int
  putStrLn $ map (f . g n) l2

f c
  | c > 'Z' = chr $ (ord c) - 26
  | otherwise = c

g 0 c = c
g n c = succ $ g (n - 1) c