APanoramixsPrediction.hs

module Main where
import Control.Applicative
import Data.List
import Data.Maybe
import Data.Function (on)
import Text.Printf

splitBy :: (a -> Bool) -> [a] -> [[a]]
splitBy p [] = []
splitBy p xs = a : (splitBy p $ dropWhile p $ b)
   where
     (a, b) = break p xs
 
split :: String -> [String]
split = splitBy (==' ')


primes3 = 2:f [3] [3,5..]
    where f (x:xs) ys = let (ps, qs) = span (< x^2) ys
                        in  ps ++ f (xs ++ ps) [z | z <- qs, mod z x /= 0]


input = lines <$> readFile "input.txt"


f n m = if m==m' then "YES" else "NO"
    where
      [_,m'] = take 2 . dropWhile (<n) $ primes3 

rr :: String -> Integer
rr = read

main :: IO ()
main = 
    do {ns <- (map $ map $ rr) . (map split)<$> lines<$>getContents
       ; mapM_ (\ [n,m] -> printf "%s\n" . f n $ m) ns 
       }