At noon on the day of the Giant Cup exam, 6 invigilators bought boxed lunches. If they bought 7 boxes and shared them, everyone would be full. The box is not enough for everyone to eat. Later, several teachers came, and in the end, I bought a few more boxes of lunch, just enough for everyone to eat, and there was nothing left. If every teacher has the same appetite, then at least how many teachers came later.
巨人杯考试的这一天中午，6个监考老师买盒饭吃，如果买7盒分着吃可以让大家都吃饱，但还有剩余；此时又来了一位老师，结果发现再多买一盒还不够大家吃．后来又来了若干位老师，结果再多买几盒盒饭刚好够大家吃，而且没有剩余．如果每个老师的饭量都一样，那么后来至少来了多少位老师．
<result>2</result>