Let's call a positive integer composite if it has at least one divisor other than $1$ and itself. For example:

• the following numbers are composite: $1024$, $4$, $6$, $9$;
• the following numbers are not composite: $13$, $1$, $2$, $3$, $37$.

You are given a positive integer $n$. Find two composite integers $a,b$ such that $a-b=n$.

It can be proven that solution always exists.