1 2–3 4–5 6–7 8–9 10–11 12–13 14–15 16–17 18–19 20–21 22–23 24–25 26–27 28–29 30–31 32–33 34–35 36–37 38–39 40–41 42–43 44–45 46–47 48–49 50–51 52–53 54–55 56–57 58–59 60–61 62–63 64–65 66–67 68