Two cars with speeds v1 and v2 are headed toward one another

Two cars with speeds v1 and v2 are headed toward one another along a straight level road. When they are in the distance d apart, each driver sees the other’s car and applies the brakes. Assuming both cars have equal magnitude accelerations after the brakes are applied, derive an algebraic formula for the minimum magnitude of this acceleration which avoid a collision in terms of v1, v2, and d.