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