n = int(input())
res = 0
dic = {}
for i in range(n):
  abc = [int(x) for x in input().split()]
  for key in abc:
    if key in dic:
      dic[key] += 1
    else:
      dic[key] = 1
    
    if dic[key] == 2:
      res += 1
      dic[key] -= 2

cnt = 0
for k,v in dic.items():
  if v >= 1:
    cnt += 1
res += cnt // 4

print(res)