import strutils
import sequtils
import intsets

var
  N       = stdin.readLine.parseInt
  ans     = 0
  counter = initIntSet()

for _ in 0 ..< N:
  var abc = stdin.readLine.split.map(parseInt)
  for item in abc:
    if item in counter:
      ans += 1
      excl counter, item
    else:
      incl counter, item

ans += counter.len div 4

echo ans