There are 12 steps in a staircase, and it is stipulated that each step can take 1 step or 2 steps, and a maximum of 3 steps can be taken. From the ground to the top step, how many different ways can there be?
一个楼梯共有12级台阶，规定每步可以迈1级台阶或2级台阶，最多可以迈3级台阶．从地面到最上面1级台阶，一共可以有多少种不同的走法？
<gadget id="calculator">2 + 4 + 7</gadget>
<output>13</output>

<gadget id="calculator">4 + 7 + 13</gadget>
<output>24</output>

<gadget id="calculator">7 + 13 + 24</gadget>
<output>44</output>

<gadget id="calculator">13 + 24 + 44</gadget>
<output>81</output>

<gadget id="calculator">24 + 44 + 81</gadget>
<output>149</output>

<gadget id="calculator">44 + 81 + 149</gadget>
<output>274</output>

<gadget id="calculator">81 + 149 + 274</gadget>
<output>504</output>

<gadget id="calculator">149 + 274 + 504</gadget>
<output>927</output>

<result>927</result>