The vertices of a parallelogram $\mathrm{ABCD}$ are $\mathrm{A}\left(3,1\right),\mathrm{B}\left(13,6\right),\mathrm{C}\left(13,21\right)$ and $\mathrm{D}\left(3,16\right)$. If a line passing through the origin divides the parallelogram into two congruent parts, then the slope of the line is