text: --1270. All People Report to the Given Manager
  --
  --Table: Employees
  --
  --+---------------+---------+
  --| Column Name   | Type    |
  --+---------------+---------+
  --| employee_id   | int     |
  --| employee_name | varchar |
  --| manager_id    | int     |
  --+---------------+---------+
  --employee_id is the primary key for this table.
  --Each row of this table indicates that the employee with ID employee_id and name employee_name reports his work to his/her direct manager with manager_id
  --The head of the company is the employee with employee_id = 1.
  --
  --
  --Write an SQL query to find employee_id of all employees that directly or indirectly report their work to the head of the company.
  --
  --The indirect relation between managers will not exceed 3 managers as the company is small.
  --
  --Return result table in any order without duplicates.
  --
  --The query result format is in the following example:
  --
  --Employees table:
  --+-------------+---------------+------------+
  --| employee_id | employee_name | manager_id |
  --+-------------+---------------+------------+
  --| 1           | Boss          | 1          |
  --| 3           | Alice         | 3          |
  --| 2           | Bob           | 1          |
  --| 4           | Daniel        | 2          |
  --| 7           | Luis          | 4          |
  --| 8           | Jhon          | 3          |
  --| 9           | Angela        | 8          |
  --| 77          | Robert        | 1          |
  --+-------------+---------------+------------+
  --
  --Result table:
  --+-------------+
  --| employee_id |
  --+-------------+
  --| 2           |
  --| 77          |
  --| 4           |
  --| 7           |
  --+-------------+
  --
  --The head of the company is the employee with employee_id 1.
  --The employees with employee_id 2 and 77 report their work directly to the head of the company.
  --The employee with employee_id 4 report his work indirectly to the head of the company 4 --> 2 --> 1.
  --The employee with employee_id 7 report his work indirectly to the head of the company 7 --> 4 --> 2 --> 1.
  --The employees with employee_id 3, 8 and 9 don't report their work to head of company directly or indirectly.
  
  --# Write your MySQL query statement below
  select e3.employee_id from Employees e1, Employees e2, Employees e3
  where e1.manager_id = 1 and e2.manager_id = e1.employee_id and e3.manager_id = e2.employee_id and e3.employee_id != 1