Help with genotype blood question please

The parents of two children are O+ and A+. The children are O- and A+. What can you deduce about the genotypes of the parents?

O+ parent has to be OO.
A+ parent can be AA or AO.
However since one child is O-, A+ parent must be AO because the O- child receives one O allele from each parent.
Since both parents are Rh+, they can be +/+ or +/-.
However again since one child is O-, and he has received one - allele from each parent, both parents must be +/-.