from decimal import Decimal

K = int(input())

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

count = 0

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

probability = Decimal(count) / Decimal(36)
print("{0:.17f}".format(probability))