python
class Solution:
def numberOfPairs(self, nums: List[int]) -> List[int]:
nums.sort()
answer = [0,len(nums)]
i = 0
while i<len(nums)-1:
if(nums[i]==nums[i+1]):
answer[0] +=1
answer[1] -=2
i += 2
else:
i +=1
return answer