Several children buy two kinds of goods with unit price of 3 yuan and 5 yuan, and each person buys at least one piece, but the total amount of goods purchased by each person shall not exceed 15 yuan. Xiaomin said: There must be at least three of the children who bought the same quantity of the two commodities. Q: How many children are there at least?
若干名小朋友购买单价为3元和5元的两种商品，每人至少买一件，但每人购买的商品的总金额不得超过15元．小民说：小朋友中一定至少有三人购买的两种商品的数量完全相同．问：至少有多少名小朋友？
<gadget id="calculator">3 - 1</gadget>
<output>2</output>

<gadget id="calculator">2 * 12</gadget>
<output>24</output>

<gadget id="calculator">24 + 1</gadget>
<output>25</output>

<result>25</result>