Entering on Greencard with return ticket

[immihelp]

I would like some info on entering the U.S.A. :

I went to my interview at Napoli on Ago.3rd and was givin my immigrant
visa to enter the united states within 6 months.

My question is: do I need to arrive to the United States with a one way
ticket?

One way tickects are twice as much as a round way ticket. Will I have any problems at immigration when entering the U.S.A.? I will thank you for the information,

[immihelp]

You can have return ticket.