1234567891012141618202224262830323436384042444648505254565860626466 Al X1 2 3 4 5 6 7 8 9 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 A1 X1 X2 A2