Untitled

import random

staywin = 0
total = 0
for i in xrange(1000):
  doors = ['GOOD', 'CAR', 'BAD']
  i = random.randint(0, 1)
  j = random.randint(1, 2)
  if i == j:
    continue
  total += 1
  if doors[i] == 'GOOD':
    staywin += 1


print(float(staywin) / total)