The yearly sports meeting is approaching in Hail university and $M$ departments, conveniently numbered from 1 to $M$, are going to take part in. Each department has no more than $h$ students.
Now send $a_i$ students from the $i$-th department as spectators, such that $\sum\limits_{i=1}^{M}a_i=L$. There are $k$ seats every row on the grandstand and $L \bmod k = 0$. Students from the same department are required to sit in the same row. The question is how many rows should be arranged at least, to ensure that no matter of the values of $M$ and $a_1, \cdots, a_m$, all the students will be able to get seated.