A compression member made of steel has a 720 -mm effective length and must support the 198 -kN load $\mathbf{P}$ as shown. For the material used $\sigma_{Y}=250 \mathrm{MPa}$ and $E=200 \mathrm{GPa}$. Using the interaction method with an allowable bending stress equal to $150 \mathrm{MPa}$ determine the smallest dimension $d$ of the cross section that can be used.