class Solution(object):
def removeDuplicates(self, nums):
"""
:type nums: List[int]
:rtype: int
"""
n=len(nums)
if n<=2:
return n
start=1
for i in range(2,n):
if nums[i]!=nums[start] or nums[i]!=nums[start-1]:
start+=1
nums[i],nums[start]=nums[start],nums[i]
return start+1
