def main():
    Z = [2, 3, 5, 7, 11, 13]
    X = [4, 6, 8, 9, 10, 12]
    A = int(input())
    cnt = 0
    for z in Z:
        for x in X:
            if z * x == A:
                cnt += 1
    print(f'{cnt/36:.15f}')


if __name__ == '__main__':
    main()