Xiao Ming has two stamps with denominations of 3 cents, 5 cents and 8 cents each. How many different postages can he pay with these stamps.
小明有面值为3角、5角、8角的邮票各两枚．他用这些邮票能付多少种不同的邮资．
<gadget id="calculator">3 + 5 + 4 + 3 + 2 + 1</gadget>
<output>18</output>

<result>18</result>