Children climb a tall structure and gather at the top in an obstacle challenge.
Children are climbing something.
Answer: Somethings refers to the obstacle challenge
exists s1 x1 x2 x3 x4.(n_top(x2) & a_topic(s1) & subset_of(x1,s1) & at(x1,x2) & in(x2,x3) & n_challenge(x3) & of(x3,x4) & n_obstacle(x4) & n_gather(x1) & all s2 x5.((n_structure(x5) & a_tall(s2) & Theme(s2,x5)) -> exists x6 x7.(subset_of(x6,s1) & for(x6,x5) & n_climb(x6) & (x6 = x7) & ne_nam_children(x7))))
exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_climb(e1) & n_thing(x2) & n_child(x1))