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module Main where
import Control.Monad (liftM2)
main :: IO ()
main = print $ primePalindromes [1 .. 1000]
primePalindromes :: [Int] -> [Int]
primePalindromes = filter (liftM2 (&&) isPalindrome isPrime)
isPrime :: Int -> Bool
isPrime n = n > 1 && null [x | x <- [2 .. (isqrt n)], n `mod` x == 0]
isPalindrome :: Int -> Bool
isPalindrome = liftM2 (==) show (reverse . show)
isqrt :: Int -> Int
isqrt = floor . sqrt . fromIntegral
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