# No.211 素数サイコロと合成数サイコロ(1)
primes = [2, 3, 5, 7, 11, 13]
composites = [4, 6, 8, 9, 10, 12]
k = int(input())
count = 0

for i in primes:
    for j in composites:
        if i * j == k:
            count += 1

print('{:.12f}'.format(count / 36))