# mortgage.py

principle  = 500000        # Initial principle
payment    = 499           # Monthly payment
rate       = 0.04          # The interest rate
total_paid = 0             # Total amount paid
months     = 0             # Number of months

while principle > 0:
      principle = principle*(1+rate/12) - payment
      total_paid += payment
      months     += 1
      if months == 24:
          rate    = 0.09
          payment = 3999

print "Total paid", total_paid
print "Months", months