The school held a sports meeting, and a total of 54 people participated in it. Everyone has a participating number. It is known that the number of the previous person is always 4 less than the number of the next person. The number of the last person is 215. What is the number of the first person? ?
学校举办运动会，共54人参加，每人都有参赛号码，已知前一个人的号码比后一个人的号码总是少4，最后一个人的号码是215，第一个人的号码是多少？
<gadget id="calculator">54 - 1</gadget>
<output>53</output>

<gadget id="calculator">53 * 4</gadget>
<output>212</output>

<gadget id="calculator">215 - 212</gadget>
<output>3</output>

<result>3</result>