In which
A is the amount the United States is entitled to recover;
0 is the sum of the total amount paid to the individual for the months of postdoctoral support up to a maximum of twelve months;
t is total number of months in the individual's service obligation;
and s is the number of months of the obligation served by him or her in accordance with paragraph (a) or (b) of this section.
42 C.F.R. §66.110