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 Ruby (2.3.3) (judge verdict: Runtime Error)

data = $stdin.read.strip
result = []
max = 0
data.size.times do |i|
  if acgt?(data[i])
    result << data[i]
  else
    result = []
  end

  if max < result.size
    max = result.size
  end
end
puts max

def acgt?(c)
  %w{A C G T}.include?(c)
end