You need to iterate _through_ the members of the deque.
Deques are nice general STL containers so you can do this in two ways. In the first, you can treat the deque like an array, and just make a for loop to go through it, using req[i].size() as your loop end condition - i.e., access each student _in_ each deque using req[i][j] as a way to reference each thing.
Alternatively, and in _much better_ STL style, you could use an iterator - make an iterator using deque<Student>::iterator iter = req[i].begin(), and iterate through the members from there. I'd give you code for that, but that's really doing all the work for you
EDIT: Sorry, had .front(), where I should've had .begin(). More the fool me!