101440: [AtCoder]ABC144 A - 9x9
Memory Limit：256 MB
Time Limit：2 S
Judge Style：Text Compare
Creator：
Submit：0
Solved：0
Description
Score : $100$ points
Problem Statement
Having learned the multiplication table, Takahashi can multiply two integers between $1$ and $9$ (inclusive) together. He cannot do any other calculation.
Given are two integers $A$ and $B$.
If Takahashi can calculate $A \times B$, print the result; if he cannot, print -1 instead.
Constraints
- $1 \leq A \leq 20$
- $1 \leq B \leq 20$
- All values in input are integers.
Input
Input is given from Standard Input in the following format:
$A$ $B$
Output
If Takahashi can calculate $A \times B$, print the result; if he cannot, print -1.
Sample Input 1
2 5
Sample Output 1
10
$2 \times 5 = 10$.
Sample Input 2
5 10
Sample Output 2
-1
$5\times 10 = 50$, but Takahashi cannot do this calculation, so print -1 instead.
Sample Input 3
9 9
Sample Output 3
81