A12931 | Forgetting Things

Kolya is very absent-minded. Today his math teacher asked him to solve a simple problem with the equation $a + 1 = b$ with positive integers $a$ and $b$ , but Kolya forgot the numbers $a$ and $b$ . He does, however, remember that the first (leftmost) digit of $a$ was $d_a$ , and the first (leftmost) digit of $b$ was $d_b$ .

Can you reconstruct any equation $a + 1 = b$ that satisfies this property? It may be possible that Kolya misremembers the digits, and there is no suitable equation, in which case report so.

The only line contains two space-separated digits $d_a$ and $d_b$ ( $1 \leq d_a, d_b \leq 9$ ).

If there is no equation $a + 1 = b$ with positive integers $a$ and $b$ such that the first digit of $a$ is $d_a$ , and the first digit of $b$ is $d_b$ , print a single number $-1$ .

Otherwise, print any suitable $a$ and $b$ that both are positive and do not exceed $10^9$ . It is guaranteed that if a solution exists, there also exists a solution with both numbers not exceeding $10^9$ .