The compound shown is 1,3-dimethylcyclohexane with no configuration specified. Treating the ring as planar and counting configurational stereoisomers only (cis, trans and enantiomers), how many stereoisomers does it have? Give the answer as an integer.

C1 and C3 are equivalent stereocentres. The cis isomer (both $\mathrm{CH}{}_3$ on the same face) has a mirror plane through C2 and C5, so it is a single meso compound. The trans isomer has no mirror plane and exists as a pair of enantiomers, (1R,3R) and (1S,3S). Total = 1 + 2 = 3 (explicit enumeration gives 3 distinct stereoisomers, one achiral).