K =int(input())
P = [2,3,5,7,11,13]
C = [4,6,8,9,10,12]
D = []

for x in P:
    for y in C:
        D.append(x*y)

if D.count(K) == 0:
    print('0.00000000000000000')
else:
    print(D.count(K)/36)