import sys
from decimal import Decimal, getcontext

getcontext().prec = 25  # Sufficient precision to handle 18 decimal places

prime = [2, 3, 5, 7, 11, 13]
composite = [4, 6, 8, 9, 10, 12]

K = int(sys.stdin.readline())

count = 0
for p in prime:
    for c in composite:
        if p * c == K:
            count += 1

probability = Decimal(count) / Decimal(36)

# Format to 18 decimal places
print("{0:.18f}".format(probability))