The flow stress (in $MPa$) of a material is given by

$\sigma =500\varepsilon ^{0.1}$,

where $ε$ is true strain. The Young’s modulus of elasticity of the material is $200$ $GPa$. A block of thickness $100$ $mm$ made of this material is compressed to $95$ $mm$ thickness and then the load is removed. The final dimension of the block (in $mm$) is _________