Find equilibrium constant for reaction at same temperature

Question

The following equilibrium constants have been determined for hydrosulfuric acid at 25°C.

H₂S(aq) H+(aq) + HS -(aq) K'c = 9.5 10-8

HS -(aq) H+(aq) + S₂-(aq) K"c = 1.0 10-19

Calculate the equilibrium constant for the following reaction at the same temperature.

H₂S(aq) 2H+(aq) + S₂-(aq)