An ideal opamp has voltage sources $V_1, V_3, V_5, \dots, V_{N-1}$ connected to the non-inverting input and $V_2, V_4, V_6, \dots, V_N$ connected to the inverting input as shown in the figure below $(+V_{CC}= 15$ volt, $ – V_{CC} = – 15$ volt). The voltages $V_1, V_2, V_3, V_4, V_5, V_6, \dots $ are $1, -1/2, 1/3, -1/4, 1/5, -1/6, \dots$ volt, respectively. As $N$ approaches infinity, the output voltage (in volt) is _________
