Can anyone please explain how to solve the following problem or the formula for it

Problem Description

In a conference, attendees are invited for a dinner after the conference.

The Coordinator, Sagar arranged round tables for dinner and want to have

an impactful seating experience for the attendees. Before finalizing the

seating arrangement, he want to analyze all possible arrangements. There

are R round tables and N attendees. In case where N is an exact multiple

of R, the number of attendees must be exactly N/R. If N is not an exact

multiple of R, then the distribution of attendees must be as equal as

possible. Please refer Example section for better understanding.

For example, R =2 and N=3

All possible seating arrangements are

(1,2) & (3)

(1,3) & (2)

(2,3) & (1)

Attendees are numbered from 1 to N.

Constraints

0 < R <= 10 (Integer)

0 < N <= 20 (Integer)

Input Format

One line containing two space delimited integers R and N, where R

denotes the number of round tables and N denotes the number of

attendees

Output

Single integer S denoting number of possible unique arrangements

Test case:

Input

2 5

Output

10

Explanation

R=2, N=5

- (1,2,3) & (4,5)
- (1,2,4) & (3,5)
- (1,2,5) & (3,4)
- (1,3,4) & (2,5)
- (1,3,5) & (2,4)
- (1,4,5) & (2,3)
- (2,3,4) & (1,5)
- (2,3,5) & (1,4)
- (2,4,5) & (1,3)
- (3,4,5) & (1,2)

Arrangements like

(1,2,3) & (4,5)

(2,1,3) & (4,5)

(2,3,1) & (4,5), etc.

But, as it is a round table, all the above arrangements are same