postgresql - Get repeated values -

i have table this:

i need numbers, wich repeated in different citys , these citys quantity each number.

that table, need result:

number | repeated citys quantity  ---------- 222    | 2 

because number 222 repeated in 2 different city.

i have solution:

1) greate function returns unique values array, example array_unique()

2) , then:

select number, array_length(uniq_city_list, 1) (     select number, array_unique(array_agg(city)) uniq_city_list mytable     group number ) t array_length(uniq_city_list, 1) > 1 

but, may there better solution doing this? think not optimal query...

select number, count(*) (     select number, city     t     group number, city ) s group number having count(*) > 1 order number