A cascade connection of two voltage amplifiers A1 and A2 is shown in the figure. The open-loop gain Av0, input resistance Rin, and output resistance Ro for A1 and A2 are as follows:
A1: Av0 = 10, Rin = 10 kΩ, R0= 1 kΩ.
A2: Av0 = 5, Rin = 5 kΩ, R0 = 200 Ω.
The approximate overall voltage gain vout/vin is __________