If insulin were treated with mercaptoethanol to break its disulfide bonds, and then the mercaptoethanol were removed

Question:

If insulin were treated with mercaptoethanol to break its disulfide bonds, and then the mercaptoethanol were removed so that disulfide bonds could re-form, how many different ways could the two polypeptide chains become linked to each other (assuming that one or two disulfide bonds can form between the two chains)?