A Quiet Minute

Same desks at Meridian Utilities, same model: the number of calls a desk takes in a minute is Poisson with that desk's own average.

This time the question comes from the other direction. The operations lead is arguing for giving agents a queue of written tickets to work through between calls, and to make the case she needs to know how much genuinely dead air there is - minutes in which the phone does not ring at all. "Never happens" is the working assumption on the floor, and she suspects it is wrong. She wants the figure for the busy desks as well as the quiet ones, because the answer to her argument is different on each.

Task: Print the probability that no calls at all arrive in a given minute, under a Poisson model with the stated mean, rounded to 4 decimals.

Input

One line holding the desk's average number of calls per minute, a positive decimal.

Output

One line holding the probability, rounded to 4 decimals and printed the way Python prints a float - 0.0183.

Example:

Input:
4

Output:
0.0183