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n = int(input())
s = 0
k = 0
for i in range(n):
  a, b = map(int, input().split())
  now = max(a, b, c)
  s += now
  arr = [a, b, c]
  for c in arr:
  	if (abs(c-now) < k or k == 0) and abs(c-now) % 4 != 0 and now != c:
      k = abs(c-now)

if s % 4 == 0 and k == 0:
  print(0)
elif s % 4 == 0:
  print(s-k)
else:
  print(s)
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