def doit(list1, list2):
lastmatch = -1
lastunmatch = -1
for i, x in enumerate(zip(list1, list2)):
if x[0] == x[1]:
lastmatch = i
else:
lastunmatch = i
print abs(lastmatch - lastunmatch)
list1 = ['cat', 'sat', 'on', 'mat', 'xx', 'yy']
list2 = ['cow', 'sat', 'on', 'carpet', 'xx', 'yy']
doit(list1, list2)
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