Counting Perfect Squares

Problem Description

Xiaoyang is studying perfect squares.

Square: the square of a number equals the number multiplied by itself.

Perfect square: a number that can be expressed exactly as the square of some positive integer.

For example, $9$ is a perfect square because $9 = 3^2 = 3 \times 3$; but $27$ is not, because $27$ cannot be expressed as the square of any positive integer.

Given two positive integers $l$ and $r$ (it is guaranteed that $l \le r$), Xiaoyang wants to know how many integers in the range from $l$ to $r$ inclusive are perfect squares.

Input Format

Two lines of input. The first line is a positive integer $l$. The second line is a positive integer $r$.

Output Format

Output a non-negative integer: the count of perfect squares among the integers from $l$ to $r$. If there is no perfect square in $[l, r]$, output $0$.

Sample Input

1
21

Sample Output

4

Sample Explanation

For the sample, $l=1$, $r=21$. The perfect squares between $1$ and $21$ are $1^2=1$, $2^2=4$, $3^2=9$, $4^2=16$, four in total, so output $4$.

Constraints

$1 \le l \le r \le 2000$