The following isothermal autocatalytic reaction, A+B⟶2B (-r_A)=0.1C_AC_B(mol L^-1s^-1) is carried out in an ideal continuous stirred tank reactor (CSTR) operating at steady state. Pure A at 1 mol L^-1 is fed, and 90% of A is converted in the CSTR. The space time of the CSTR is _______ seconds.