In order to welcome March 15, the neighborhood committee of Guangming Community intends to purchase some small saplings from the forest farm. Aunt Li of the neighborhood committee found that some small saplings in the forest farm were arranged in a three-layer hollow square, with 6 trees on each side of the innermost layer. Aunt Li bought all these small saplings and mobilized the residents of the community to plant them on a road in the south of the community. This road is 400 meters long. Trees are only planted on one side of the road, and both ends are planted, every 5 meters. Plant one. So, how many saplings are left in the end?
为了迎接3.15，光明社区居委会打算从林场采购一些小树苗．居委会李大妈发现，林场的一些小树苗排成一个三层的空心方阵，最里层每条边有6棵树．李大妈将这些小树苗全部买下来，发动小区居民将这些树苗种在小区南边的一条马路上，这条马路长400米，只在马路的一侧种树，并且两头都种，每隔5米种一棵．那么，最后还剩多少棵小树苗？
<gadget id="calculator">6 + 2 + 2</gadget>
<output>10</output>

<gadget id="calculator">10 - 3</gadget>
<output>7</output>

<gadget id="calculator">7 * 3 * 4</gadget>
<output>84</output>

<gadget id="calculator">400 / 5</gadget>
<output>80</output>

<gadget id="calculator">80 + 1</gadget>
<output>81</output>

<gadget id="calculator">84 - 81</gadget>
<output>3</output>

<result>3</result>