output_description: Print the letter representing the base that bonds with the base b.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      b
attempt: def atgc(base):
      b = base.lower()
      if b in ["a", "t", "g", "c"]:
          if b == "a":
              return "T"
          elif b == "t":
              return "A"
          elif b == "g":
              return "C"
          elif b == "c":
              return "G"
  
problem_description: 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.
samples: [{"input": "A", "output": "T\n    \n\n* * *"}, {"input": "G", "output": "C"}]