As shown in Figure 1, there is a processing unit which reads two positive input values
A1 and A2, and then writes two output values B1 and B2. B1 is equal to A2, and B2 is
the remainder of A1 divided by A2. In Figure 2, two processing units with the same
function as the above are connected in series. When A1=15 and A2=6 are given to
the left-hand unit in Figure 2, what is the output value of B2 for the right-hand unit?