In a fierce battle, 100 soldiers participated in the battle, 70 of them lost an eye; 75 lost an ear; 80 soldiers lost a hand; 85 lost a foot. Question: At least how many soldiers lost one eye, one ear, one hand, and one foot at the same time.
在一次激烈的战争中，有100名士兵参战，其中70名失去了一只眼睛；75名失去了一只耳朵；80名士兵失去了一只手；85名失去了一只脚．问：同时失去了一只眼睛，一只耳朵，一只手，一只脚的士兵至少有多少个．
<gadget id="calculator">100 - 70</gadget>
<output>30</output>

<gadget id="calculator">100 - 75</gadget>
<output>25</output>

<gadget id="calculator">100 - 80</gadget>
<output>20</output>

<gadget id="calculator">100 - 85</gadget>
<output>15</output>

<gadget id="calculator">30 + 25 + 20 + 15</gadget>
<output>90</output>

<gadget id="calculator">100 - 90</gadget>
<output>10</output>

<result>10</result>