Problem: Given is an integer N.

Takahashi chooses an integer a from the positive integers not greater than N with equal probability.

Find the probability that a is odd.

Constraints

* 1 \leq N \leq 100

Input

Input is given from Standard Input in the following format:


N


Output

Print the probability that a is odd. Your output will be considered correct when its absolute or relative error from the judge's output is at most 10^{-6}.

Examples

Input

4


Output

0.5000000000


Input

5


Output

0.6000000000


Input

1


Output

1.0000000000

Solution (in PYTHON):

Solution:
import sys
from collections import deque
import copy
import math
def get_read_func(fileobject):
    if fileobject == None :
        return raw_input
    else:
        return fileobject.readline



def main():
    if len(sys.argv) > 1:
        f = open(sys.argv[1])
    else:
        f = None
    read_func = get_read_func(f);
    input_raw = read_func().strip().split()
    [N] = [int(input_raw[0])]
    print float((N / 2) + (N % 2)) / float(N)


if __name__ == '__main__':
    main()