Current Electricity

A wire of uniform cross section and resistance 4 ohms is bent in the shape of square ABCD. Point A is connected to a point \(\mathrm{P}\) on DC by a wire AP of resistance \(1 \mathrm{ohm}\). When a potential difference is applied between \(\mathrm{A}\) and \(\mathrm{C}\), the points \(\mathrm{B}\) and \(\mathrm{P}\) are seen to be in same potential. What is the resistance of part \(\mathrm{DP}\) ?