100 atcoder#ABC144A. [ABC144A] 9x9
[ABC144A] 9x9
Score : points
Problem Statement
Having learned the multiplication table, Takahashi can multiply two integers between and (inclusive) together. He cannot do any other calculation.
Given are two integers and .
If Takahashi can calculate , print the result; if he cannot, print -1
instead.
Constraints
- All values in input are integers.
Input
Input is given from Standard Input in the following format:
Output
If Takahashi can calculate , print the result; if he cannot, print -1
.
2 5
10
.
5 10
-1
, but Takahashi cannot do this calculation, so print -1
instead.
9 9
81