# A^B == B^A?

Time Limit: 1 Second Memory Limit: 32768 KB

Solve the equation in the name of this problem.

## Input

There are several cases. Each of them has a single real number as the smaller one of a and b in the equation on a separate line. You may assume it's no smaller than 1.1. Proceed until the end of file.

## Output

For each case, print the other number on a single line. Keep 5 digits after decimal point. If no such number exists, print -1.

## Sample Input

2 10

## Sample Output

4.00000 -1Submit

Source: ZOJ 3rd Anniversary Contest