{-# LANGUAGE BangPatterns #-}

import qualified Data.ByteString.Char8 as C
import Data.Vector.Unboxed
  (foldl1', generate, prescanl', prescanr', replicate, reverse, zipWith4)
import Prelude hiding (replicate, reverse)

main = print =<< sol <$> readLn <*> (C.length <$> C.getLine)

sol k n = foldl1' (.+.) $ zipWith4 (\a b c d -> a .*. b .*. c .*. d) c1 c2 p1 p2
  where
  c1 = prescanl' (.*.) (fac (n-1)) $ generate (k+1) (n+)
  c2 = prescanr' (.*.) (inv $ fac (n-1)*fac k) $ generate (k+1) id
  p1 = prescanl' (.*.) 1 $ replicate (k+1) 25
  p2 = reverse . prescanl' (.*.) 1 $ replicate (k+1) 26

(.*.) = ((`mod` p) .) . (*)
(.+.) = ((`mod` p) .) . (+)

p = 10^9+7 :: Int

inv 1 = 1
inv !a = pwr a (p-2)

pwr !a !n
  | n == 0    = 1
  | odd n     = a .*. r
  | otherwise = r
  where
  q = pwr a (n `div` 2)
  r = q .*. q

fac 0 = 1
fac !n = n .*. fac (n-1)