A wire of length $\mathrm{L}$ and radius $\mathrm{r}$ is clamped rigidly at one end. When the other end of the wire is pulled by a force $\mathrm{F}$, its length increases by $5 \mathrm{~cm}$. Another wire of the same material of length $4 \mathrm{L}$ and radius $4 \mathrm{r}$ is pulled by a force $4 \mathrm{F}$ under same conditions. The increase in length of this wire is __________________ $\mathrm{cm}$.