1099-S Sale of Second Home

I have sold a second home (a home that was for my Father in Law - he didn't pay rent or anything - just his own utilities). I received from the Title company a Substitute 1099-S which shows the gross proceeds from the sale of $135,000. I had a mortgage on this home of $45,000. How is this reported under the investments section in TurboTax? Would it be the gross proceeds or the net proceeds?