The total number of reagents from those given below, that can convert nitrobenzene into aniline is __________. (Integer answer)
\( \mathrm{I.}\ \mathrm{Sn} - \mathrm{HCl} \)
\( \mathrm{II.}\ \mathrm{Sn} - \mathrm{NH_4OH} \)
\( \mathrm{III.}\ \mathrm{Fe} - \mathrm{HCl} \)
\( \mathrm{IV.}\ \mathrm{Zn} - \mathrm{HCl} \)
\( \mathrm{V.}\ \mathrm{H_2} - \mathrm{Pd} \)
\( \mathrm{VI.}\ \mathrm{H_2} - \text{Raney Nickel} \)