Scanf.scanf "%d" (fun n ->
    let rec loop i ax ay bx by cx cy =
        if i = n then (if (ax, ay, bx, by, cx, cy) = (5, 8, 4, 8, 6, 8) then "YES" else "NO") else
        Scanf.scanf " %d %d %d %d" (fun x1 y1 x2 y2 ->
            if ax = x1 && ay = y1 then loop (i + 1) x2 y2 bx by cx cy else
            if bx = x1 && by = y1 then loop (i + 1) ax ay x2 y2 cx cy else
            if cx = x1 && cy = y1 then loop (i + 1) ax ay bx by x2 y2 else
                                       loop (i + 1) ax ay bx by cx cy
        )
    in
    loop 0 2 8 3 9 7 9 |> print_endline
)