import re
import math
 
class RateStrategyParser:
 
  COMMAND = re.compile(r'^minimum\s+(\d+)\s+(\w+)\s*,\s*'+
                       r'nextcharge\s+(\d+)\s+(\w+)\s*'+
                       r'(:\s*(\d+)\s*%)?$', re.I)
 
  def __init__(self, str):
    m = self.COMMAND.match(str)
    if m:
      match = m.groups()
      self.minimum = self._convert_time(match[0], match[1])
      self.nextcharge = self._convert_time(match[2], match[3])
      if match[4]:
        self.nextcharge_rate = float(match[5])/100.0
      else:
        self.nextcharge_rate = 1.0
    else:
      raise Exception("Unable to parse input: %s" % str)
 
  def calculate(self, price, time):
    total = 0
    if time > self.minimum:
      time -= float(self.minimum)
      total = price+math.ceil(time/self.nextcharge)*self.nextcharge_rate*price
    return total
 
  def _convert_time(self, time, unit):
    for exp, factor in [(r's|sec|seconds?', 1),
                        (r'm|min|minutes?', 60),
                        (r'h|hours?', 3600)]:
      if re.match(exp, unit):
        return int(time)*factor
    raise Exception("Unknown Unit: %s %s" % (time, unit))
 
if __name__ == '__main__':
  rp = RateStrategyParser("minimum 1 min, nextcharge 6 sec : 10%")
  print "%.2f" % rp.calculate(24.0, 72)