Hint: You can arrange the two shortest in two ways and the rest can be arranged using normal permutations.
In other words, you have 5! for one arrangement of the two shortest (A then B) and also for another arrangement (B then A) if A and B are the two smallest.
Because there are no restrictions on the other five people, then it means that they can be represented in 5! or 120 ways for one particular arrangement of the two smallest people.
Note also that the arrangement of the five tallest and the two smallest is independent so you can vary both individually. In the case of independence the number of combinations is C*D where C is the number of possibilities for the first arrangement and D is the number for the second arrangement.