V
insert into user_cities (user_id,city_id) values (1,1);
insert into user_cities (user_id,city_id) values (2,2);
insert into user_cities (user_id,city_id) values (3,1);
insert into user_cities (user_id,city_id) values (3,2);
insert into user_cities (user_id,city_id) values (3,3);