let () =
  let arr = Array.make 10 0 in
  Scanf.scanf "%d\n" @@ fun n ->
  for i = 0 to n - 1 do
    Scanf.scanf "%d %d %d\n" @@ fun a b c ->
    arr.(a-1) <- arr.(a-1)+1; arr.(b-1) <- arr.(b-1)+1; arr.(c-1) <- arr.(c-1)+1
  done;
  let ans = ref 0 in
  for i = 0 to 9 do
    if arr.(i) >= 2 then (ans := !ans + arr.(i) / 2; arr.(i) <- arr.(i) mod 2)
  done;
  let n = Array.fold_left (+) 0 arr in
  Printf.printf "%d\n" (!ans + n / 4)