Figure-2.109 shows a block A on a smooth surface attached with a spring of force constant

Figure-2.109 shows a block A on a smooth surface attached with a spring of force constant k to the ceiling. In this state spring is in its natural lengthl. The block A is connected with a massless and frictionless string to another identical mass B hanging over a light and smooth pulley. Find the distance moved by A before it leaves contact with the ground