output_description: If a+b=15, print `+`; if a\times b=15, print `*`; if neither holds, print `x`.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      a b
attempt: [a,b]=list(map(int,(input().split())))
  if a*b=15:
    print("*")
  else:
    if a+b=15:
      print("+")
      else:
        print("x")
problem_description: Statement
  
  You are given two integers a and b. Determine if a+b=15 or a\times b=15 or
  neither holds.
  
  Note that a+b=15 and a\times b=15 do not hold at the same time.
samples: [{"input": "4 11", "output": "+\n    \n\n4+11=15.\n\n* * *"}, {"input": "3 5", "output": "*\n    \n\n3\\times 5=15.\n\n* * *"}, {"input": "1 1", "output": "x\n    \n\n1+1=2 and 1\\times 1=1, neither of which is 15."}]