import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines

from math import log, exp

N = int(read())

coef = [1, -6, 15, -20, 15, -6]
answer = sum(((6-i)/6) ** N * c for i,c in enumerate(coef))

print(answer)