Problems

# Big product

# Big product

The jury decided to give you a difficult task. Given numbers **a** and **b**, find the following product of numbers **a** * (**a** + **1**) * ... * **b**.

Thinking further that the task would be too boring, instead of the value of the product, the jury decided to ask you for the sign of the product. So, you need to find whether this product is positive, negative or zero.

#### Input

One line contains the integers **a** and **b** (`-10`

≤ ^{9}**a** ≤ **b** ≤ `10`

).^{9}

#### Output

Print the sign of the product **a** * (**a** + **1**) * ... * **b** - one of the next numbers "**-1**", "**0**", "**1**" correspondingly.

Input example #1

3 5

Output example #1

1

Input example #2

-6 5

Output example #2

0

Input example #3

4 9

Output example #3

1

Input example #4

-7 -1

Output example #4

-1