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 OCaml (4.02.3) (judge verdict: Accepted)

let helix =
  Scanf.scanf "%c" (fun b ->
  print_endline @@
  if b == 'A' then "T"
  else if b == 'T' then "A"
  else if b == 'G' then "C"
  else "G")
;;