Given integers \(k\) and \(n\), compute the binomial coefficient \(C(n,k)\), the number of ways to choose \(k\) elements from \(n\) distinct elements.

Input

One line containing k and \(n\), in this order.

The input satisfies:

• \(0 \le k \le n \le 66\)
• The answer fits in a signed 64-bit integer.

Output

Print \(C(n,k)\).

Example

Input

2 5

Output

10