text: #coding=utf-8
  # 分布式均值和方差计算的mapper
  import sys
  from numpy import mat, mean, power
  
  def read_input(file):
      for line in file:
          yield line.rstrip()
  
  input = read_input(sys.stdin)
  input = [float(line) for line in input]
  numInputs = len(input)
  input = mat(input)
  sqInput = power(input, 2) #对所有的值进行平方
  
  print("%d\t%f\t%f" % (numInputs, mean(input), mean(sqInput)))
  sys.stderr.write("report: still alive\n")
  
  