+--------------+---------+
| Column Name | Type |
+--------------+---------+
| product\_id | int |
| product\_name | varchar |
| unit\_price | int |
+--------------+---------+
product\_id is the primary key of this table.
Table: Sales
+-------------+---------+
| Column Name | Type |
+-------------+---------+
| seller\_id | int |
| product\_id | int |
| buyer\_id | int |
| sale\_date | date |
| quantity | int |
| price | int |
+------ ------+---------+
This table has no primary key, it can have repeated rows.
product\_id is a foreign key to Product table.
Write an SQL query that reports the buyers who have bought S8 but not iPhone. Note that S8 and iPhone are products present in the Product table.
The query result format is in the following example: