1. Solve the equation in natural numbers: $\frac{1}{x}+\frac{1}{y}=\frac{1}{3}$. In the answer, list all possible values of the number $x$ in ascending or descending order, separated by commas or semicolons.
Answer: $4,6,12\|4 ; 6 ; 12\| 12,6,4 \| 12 ; 6 ; 4$