Placing charges on a plate

A point charge +q is located at a point A which is far away from a thin dielectric square plate with positive surface charge $$+\sigma$$. It is known that the minimum work required to move the charge from point A to one of the corners of the plate is $$W_{1}=1~\mbox{J}$$. What is the minimum work $$W_{2}$$ in Joules required to move the same charge from point A to the center of the plate?

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