Problem Statement

Given are integers A and B. Find the maximum possible value of $\gcd(x, y)$ when we choose integers x and y so that A ≤ x < y ≤ B.
Here, $\gcd(x, y)$ denotes the greatest common divisor of x and y.

Input

Input is given from Standard Input in the following format:
A B

Output

Print the answer.

Constraints

• A and B are integers.
• 1 ≤ A < B ≤ $2 \times 10^5$

Sample Input 1

2 4

Sample Output 1

2

We have three ways to choose (x, y) such that A ≤ x < y ≤ B: (2,3), (2,4), (3,4), where the greatest common divisors are 1, 2, 1, respectively, so the maximum possible value is 2.

Sample Input 2

199999 200000

Sample Output 2

1

We have $\gcd(199999, 200000) = 1$.

Sample Input 3

101 139

Sample Output 3

34

见题面 Input 部分

见题面 Output 部分