Exactly 6 Calls This Minute

You're doing capacity planning for the support desks at Meridian Utilities. A year of phone logs gives each desk an average number of calls per minute, and nobody has found any bunching in them, so a desk models the number of calls in a minute as Poisson with that mean.

The rota software staffs a fixed number of agents on each desk. Before the operations lead signs off on those numbers, she wants to know how much of the day sits exactly on a given count - the minutes where a precise number of calls arrives and there is no slack left at all. She asks the question for several desks and several counts.

Task: Print the probability that exactly the stated number of calls arrives in a given minute, under a Poisson model with the stated mean, rounded to 4 decimals.

Input

Two lines: the desk's average number of calls per minute as a positive decimal, and the exact call count being asked about, a whole number of at least 0.

Output

One line holding the probability, rounded to 4 decimals and printed the way Python prints a float - 0.1042.

Example:

Input:
4
6

Output:
0.1042