10785: ABC144 - A - 9x9
[Creator : ]
Description
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.
Given are two integers $A$ and $B$.
If Takahashi can calculate $A \times B$, print the result; if he cannot, print `-1` instead.
Input
Input is given from Standard Input in the following format:
```
$A$ $B$
```
```
$A$ $B$
```
Output
If Takahashi can calculate $A \times B$, print the result; if he cannot, print `-1`.
Constraints
- $1 \leq A \leq 20$
- $1 \leq B \leq 20$
- All values in input are integers.
- $1 \leq B \leq 20$
- All values in input are integers.
Sample 1 Input
2 5
Sample 1 Output
10
$2×5=10$.
Sample 2 Input
5 10
Sample 2 Output
-1
$5\times 10 = 50$, but Takahashi cannot do this calculation, so print -1 instead.
Sample 3 Input
9 9
Sample 3 Output
81