The effect of charge exchange and photoionization of neutral hydrogen penetrating the supersonic solar wind region from the interstellar medium is taken into account by constructing appropriate source terms for the equations of the flow. The equations are solved numerically for densities of 1, 5, and 10 cm−3 in the interstellar medium. It is shown that the size of the supersonic solar wind region varies with these densities from 50 to 8 AU in the apex direction if the momentum of the incoming neutral hydrogen is neglected. If the momentum of the incoming neutral hydrogen is taken into account, it is found to be sufficient to halt the flow of the solar wind at about 45 AU for an interstellar neutral hydrogen density of 1 cm−3.