CF1225A.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.

科里亚非常心不在焉。今天他的数学老师让他解一个简单的方程 $a + 1 = b$，其中 $a$ 和 $b$ 均为正整数；但科里亚却忘记了 $a$ 和 $b$ 的具体数值。不过，他仍记得 $a$ 的首位（最左边）数字是 $d_a$，而 $b$ 的首位（最左边）数字是 $d_b$。

你能构造出任意一个满足该性质的方程 $a + 1 = b$ 吗？也有可能科里亚记错了首位数字，此时并不存在满足条件的方程，在这种情况下请报告这一点。

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

唯一的一行包含两个用空格分隔的数字 $d_a$ 和 $d_b$（$1 \leq d_a, d_b \leq 9$）。

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 $10^9$.

若不存在满足 $a + 1 = b$ 的正整数 $a$ 和 $b$，使得 $a$ 的首位数字为 $d_a$、$b$ 的首位数字为 $d_b$，则输出单个数字 $-1$。

否则，输出任意一组满足条件的正整数 $a$ 和 $b$，且二者均不超过 $10^9$。题目保证：若解存在，则必存在一组解使得两个数均不超过 $10^9$。