Multiple students sitting on stairs at a school.
Many students are in strike to fulfil their demand.
You can not assume that many students are involved. Multiple students imply more than two, but might be less than many.  There is also no evidence the students are in strike to fulfill their demand. They may just be sitting on the stairs at school.
exists e1 x1 x2 x3 x4 x5.(a_topic(x1) & at(e1,x5) & n_school(x5) & on(e1,x4) & n_stair(x4) & Actor(e1,x3) & v_sit(e1) & (x1 = x3) & n_student(x1) & (x1 = x2) & ne_nam_multiple(x2))
exists p1 x1 x3.(exists p2 x2.(in(x1,x2) & Topic(x2,p2) & exists e1.(Theme(e1,x3) & Actor(e1,x2) & v_fulfil(e1)) & n_strike(x2)) & n_demand(x3) & of(x3,x1) & n_thing(x1) & n_student(x1) & n_quantity(x1))