Every day after the father gets off work, he can just rush to the school to pick up his daughter when the school is over. One day, the school ended early, and the daughter went home by herself. After walking for 9 minutes, her father came to pick her up. The father returned home by motorcycle, and was 1 minute later than usual. The reason was that the father was 7 minutes late for getting off work. How many minutes did the school leave early for that day? ?
每天父亲下班后刚好可以在学校放学时赶到学校接女儿回家．一天，学校提早放学，女儿自己回家，走9分钟后碰到父亲来接，做父亲摩托车回家，比平时迟到1分钟，原因是父亲下班迟了7分钟，学校这天提早放学多少分钟？
<gadget id="calculator">7 - 1</gadget>
<output>6</output>

<gadget id="calculator">6 / 2</gadget>
<output>3</output>

<gadget id="calculator">3 + 1</gadget>
<output>4</output>

<gadget id="calculator">9 - 4</gadget>
<output>5</output>

<result>5</result>