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 Control.Applicative
import Data.List

-- e.g.
-- 1
-- [a] <- map read . words <$> getline => [1] -> a == 1
-- 1
-- a <- readlLn
-- 1 2 3
-- lst <- map read . words <$> getLine => [1, 2, 3]
-- 1 2 3
-- [l, m, n] <- map read . words <$. getLine :: IO [Int] => [1, 2, 3]
-- 'a'
-- c <- getChar => c == 'a'

main :: IO()
main = do
  c <- getChar
  let ans = case c of
              'A' -> 'T'
              'G' -> 'C'
              'T' -> 'A'
              'C' -> 'G'

  putStrLn [ans]