SELECT "count"(*)
FROM
  (
(
      SELECT DISTINCT
        "c_last_name"
      , "c_first_name"
      , "d_date"
      FROM
        store_sales
      , date_dim
      , customer
      WHERE ("store_sales"."ss_sold_date_sk" = "date_dim"."d_date_sk")
         AND ("store_sales"."ss_customer_sk" = "customer"."c_customer_sk")
         AND ("d_month_seq" BETWEEN 1200 AND (1200 + 11))
   ) EXCEPT (
      SELECT DISTINCT
        "c_last_name"
      , "c_first_name"
      , "d_date"
      FROM
        catalog_sales
      , date_dim
      , customer
      WHERE ("catalog_sales"."cs_sold_date_sk" = "date_dim"."d_date_sk")
         AND ("catalog_sales"."cs_bill_customer_sk" = "customer"."c_customer_sk")
         AND ("d_month_seq" BETWEEN 1200 AND (1200 + 11))
   ) EXCEPT (
      SELECT DISTINCT
        "c_last_name"
      , "c_first_name"
      , "d_date"
      FROM
        web_sales
      , date_dim
      , customer
      WHERE ("web_sales"."ws_sold_date_sk" = "date_dim"."d_date_sk")
         AND ("web_sales"."ws_bill_customer_sk" = "customer"."c_customer_sk")
         AND ("d_month_seq" BETWEEN 1200 AND (1200 + 11))
   ) )  cool_cust
;