Write a C program that corresponds to the below process tree. You are to use the

fork$()$ system call to create child processes. Additionally, your program should

ensure that the parent processes wait for their child processes to complete. As you can

see there are a total of $9$ processes $($including the parent process$).$

Output:

$1.$ Your program must print the pids of all the processes created on the screen.

$2.$ Your program must ensure that duplicate pids are not printed.

Sample Output: $./$PLfork

$--------------------------------------------------------------------------------------------------------------------$

$7615$

$7616$

$7617$

$7618$

$7619$

$7620$

$7621$

$7622$

$7623$