How many kinds of postage can be paid in total with one stamp of 80 cents, one stamp of 1.00 yuan and one stamp of 1.20 yuan.
用80分、1.00元、1.20元的邮票各一枚，一共可以支付多少种邮资．
<gadget id="calculator">3 + 3 + 1</gadget>
<output>7</output>

<result>7</result>