I have no idea how they want me to enter this answer can you

I have no idea how they want me to enter this answer, can you please help me?

The two radioactive decay series that begin with Th and end with Pb are shown in the figure (Figure 1). Identify the ten intermediary nuclei that appear in these series. Express your answer as isotopes. Enter ten nuclei in the order of the decay series separated by commas. For the pair of alternative intermediary nuclei, enter the nicleus for the upper (right) series first.

Solution

For each alpha decay mass number decreases by 4 and atomic number decreases by 2 as there is a loss of ⁴₂He

For each beta decay mass number remains constant and atomic number increases by 1 as a neutron converts to proton and leaves an electron n -> p⁺  + e^-

I have named the intermediate nuclei in alphabetical order

²²⁸88Ra , ²²⁸89 Ac   , ²²⁸₉₀ Th , ²²⁴₈₈Ra , ²²⁰₈₆Rn, ²¹⁶₈₄Po , ²¹²₈₂Pb , ²¹²₈₃Bi , ²¹²₈₄Po , ²⁰⁸₈₁Tl , Pb²⁰⁸₈₂