The open circuit parameters of 2-port network N shown in the figure, are \[\left[ {\begin{array}{*{20}{c}} {{{\text{Z}}_{11}}}&{{{\text{Z}}_{12}}} \\ {{{\text{Z}}_{21}}}&{{{\text{Z}}_{22}}} \end{array}} \right].\]   When the network is extended by a resistance R as shown in the figure, the input impedance of the network at points A, B will be