There is an error in the base Python2 code for this challenge:

q = int(raw_input().strip())
for a0 in xrange(q):
    len,c = raw_input().strip().split(' ')
    len,c = [int(len),int(c)]

Since len is being used as a variable, if I try to use the builtin len() in my function, I get a TypeError that says 'int object is not callable'.