Equilibrium const.

${\mathrm{H}}_2\mathrm{S}\left(aq\right)\rightleftharpoons {\mathrm{H}}^{+}\left(aq\right)+{\mathrm{HS}}^{-}\left(aq\right)K_1=9.5\times {10}^{-8}$

${\mathrm{HS}}^{-}\left(aq\right)\rightleftharpoons {\mathrm{H}}^{+}\left(aq\right)+{\mathrm{S}}^{2-}\left(aq\right)K_2=1.0\times {10}^{-19}$

What is the equilibrium constant for the reaction?

${\mathrm{S}}^{2-}\left(\mathrm{aq}\right)+2{\mathrm{H}}^{+}\left(\mathrm{aq}\right)\rightleftharpoons {\mathrm{H}}_2\mathrm{S}\left(\mathrm{aq}\right)K=?$