Modify the C program shown in Example $1$ in Lecture Note $2$ such that the new program will

generate one parent process and three child processes $($which all of them created by the parent

process$).$ The output of this program will show each child process PID and its parent process ID$.$

For example, $($the PID numbers can be any numbers $$ no need to be $1000,1001,1002,1003)$