output_description: Evaluate the formula and print the result.
  
  * * *
input_description: The input is given from Standard Input in the following format:
  
      
      
      A op B
attempt: eval(input())
  
problem_description: Statement
  
  Joisino wants to evaluate the formula "A op B". Here, A and B are integers,
  and the binary operator op is either `+` or `-`. Your task is to evaluate the
  formula instead of her.
samples: [{"input": "1 + 2", "output": "3\n    \n\nSince 1 + 2 = 3, the output should be 3.\n\n* * *"}, {"input": "5 - 7", "output": "-2"}]