All acyclic structural isomers of $\mathrm{C}{}_5\mathrm{H}{}_{10}$ that contain one $\mathrm{C}=\mathrm{C}$ bond (geometrical isomers counted once, i.e. constitutional isomers only) are ozonised and worked up with $\mathrm{Zn}/\mathrm{H}{}_2\mathrm{O}$. How many different carbonyl compounds are obtained in total? Give an integer.

The five constitutional isomers and their products are: pent-1-ene (methanal, butanal), pent-2-ene (ethanal, propanal), 2-methylbut-1-ene (methanal, butanone), 3-methylbut-1-ene (methanal, 2-methylpropanal), 2-methylbut-2-ene (propanone, ethanal). The distinct compounds are methanal, ethanal, propanal, butanal, propanone, butanone and 2-methylpropanal, a total of 7.