| +-------------+------+ ad_id is the column with unique values for this table. customer_id is the ID of the customer viewing this ad. timestamp is the moment of time at which the ad was shown.

Write a solution to report all the sessions that did not get shown any ads.

Return the result table in any order.

The result format is in the following example.

Examples

Example 1

Input: 
Playback table:
+------------+-------------+------------+----------+
| session_id | customer_id | start_time | end_time |
+------------+-------------+------------+----------+
| 1          | 1           | 1          |

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