CF847G University Classes

在一个大学里，有$n$个学生小组。在学习交流日里，每个小组可以参与不超过$7$个课程。总共有$7$个时间段分别称为$1$至$7$将分配给这些课程。 现在已经知道了每个小组星期一的计划，即这些小组参与课程的时间段。 你的任务是决定星期一至少需要多少个教室来供这些小组参与课程。一个教室在一个时间段只能容纳一个小组。

The first line contains a single integer $ n $ ( $ 1

Print minimum number of rooms needed to hold all groups classes on Monday.

In the first example one room is enough. It will be occupied in each of the seven time slot by the first group or by the second group. In the second example three rooms is enough, because in the seventh time slot all three groups have classes.