text: # Enter your code here. Read input from STDIN. Print output to STDOUT
  import math
  
  def cdf(std_dev, avg, x):
      inner = 1 + math.erf((x - avg) / (std_dev * math.sqrt(2)))
      return inner * 0.5
  
  ans = cdf(math.sqrt(100) * 2.0, 100 * 2.4, 250)
  
  print round(ans, 4)