1.
For positive numbers xx, yy and zz, the numerical value of the determinant
∣1log⁡xylog⁡xzlog⁡yx1log⁡yzlog⁡zxlog⁡zy1∣\begin{vmatrix} 1 & \log_x y & \log_x z \\ \log_y x & 1 & \log_y z \\ \log_z x & \log_z y & 1 \end{vmatrix}
is -