Two halves of a round homogeneous cylinder are held together by a thread wrapped round the cylinder with two equal weights. The complete cylinder weighs $31.4 \mathrm{~kg}$. The plane of contact of both of its halves is vertical. For equilibrium of both halves of the cylinder, the minimum value of $m$ is :
(a) $\frac{2}{3} \mathrm{~g}$
(b) $3.14 \mathrm{~g}$
(c) $\frac{2}{3} \mathrm{~kg}$
(d) $31.4 \mathrm{~g}$