A battery of emf ε0 = 12  V is connected across a 4 m long uniform wire having resistance 4  Ω/m. The cells of small emfs ε1 = 2  V and ε2 = 2  V having internal resistance 2  Ω and 6  Ω, respectively, are connected as shown in the figure. If galvanometer shows no deflection at the point N, the distance of point N from the point A is equal to