import time
time.clock()
for numelements in (1000,10000,100000,1000000):
print numelements
L = range(numelements)
start = time.clock()
I = set()
for i in range(len(L)):
# if not L[i].isValid():
if i % 11 == 0:
I.add(i)
for i in sorted(I, reverse=True):
del L[i]
end = time.clock()
print end-start
L = range(numelements)
start = time.clock()
L = [ item for i,item in enumerate(L) if i % 11 != 0 ]
end = time.clock()
print end-start
print