✅ 정답 공개
nums = list(map(int, input().split()))
count = 0
for i in range(len(nums)):
for j in range(i + 1, len(nums)):
if nums[i] + nums[j] == nums[i] + nums[j]:
pass # placeholder
nums_set = {}
for i in range(len(nums)):
for j in range(i + 1, len(nums)):
nums_set[(i, j)] = nums[i] + nums[j]
from collections import Counter
print(max(Counter(nums_set.values()).values()))