Mechanics hw help! i really need help with this one!!!!please?

A small m m is in the box of m M that is attached to a vertical spring of stiffness constant k. When displaced from its equilibrium position y_0 to y_1 and released, it executes simple harmonic motion. Calculate the reaction between m and M as a function of time. Does the m m always stay in contact with the box? If not, what determines that it will lose contact with the box? Calculate the value of h as measured from the equilibrium position for which it loses contact