Problem:
Score : 100 points

Problem Statement

On the Planet AtCoder, there are four types of bases: A, C, G and T. A bonds with T, and C bonds with G.

You are given a letter b as input, which is A, C, G or T. Write a program that prints the letter representing the base that bonds with the base b.

Constraints

b is one of the letters A, C, G and T.

Input

Input is given from Standard Input in the following format:

b

Output

Print the letter representing the base that bonds with the base b.

Sample Input 1

A

Sample Output 1

T

Sample Input 2

G

Sample Output 2

C

Solution in Haskell (GHC 7.10.3) (judge verdict: Accepted)

import Control.Monad
import Text.Printf

getLines :: Int -> IO [String]
getLines n = replicateM n getLine

getLinesInt :: Int -> IO [Int]
getLinesInt n = fmap read <$> getLines n

getInts :: IO [Int]
getInts = map (read :: String -> Int) . words <$> getLine

getDoubles :: IO [Double]
getDoubles = map (read :: String -> Double) . words <$> getLine

main :: IO ()
main = do
    [b] <- getLine
    putChar $ case b of 'A' -> 'T'
                        'T' -> 'A'
                        'C' -> 'G'
                        'G' -> 'C'