A child walks on a level surface from point $\text{P}$ to point $\text{Q}$ at a bearing of $30^{\circ}$, from point $\mathrm{Q}$ to point $\mathrm{R}$ at a bearing of $90^{\circ}$ and then directly returns to the starting point $\mathrm{P}$ at a bearing of $240^{\circ}$. The straight-line paths $\mathrm{PQ}$ and $\mathrm{QR}$ are $4 \mathrm{~m}$ each. Assuming that all bearings are measured from the magnetic north in degrees, the straight-line path length $\text{RP}$ (in meters) is $\_\_\_\_\_\_\_$ (rounded off to the nearest integer).