Problem: Petya loves lucky numbers. We all know that lucky numbers are the positive integers whose decimal representations contain only the lucky digits 4 and 7. For example, numbers 47, 744, 4 are lucky and 5, 17, 467 are not.

Petya and his friend Vasya play an interesting game. Petya randomly chooses an integer p from the interval [pl, pr] and Vasya chooses an integer v from the interval [vl, vr] (also randomly). Both players choose their integers equiprobably. Find the probability that the interval [min(v, p), max(v, p)] contains exactly k lucky numbers.

Input

The single line contains five integers pl, pr, vl, vr and k (1 ≤ pl ≤ pr ≤ 109, 1 ≤ vl ≤ vr ≤ 109, 1 ≤ k ≤ 1000).

Output

On the single line print the result with an absolute error of no more than 10 - 9.

Examples

Input

1 10 1 10 2


Output

0.320000000000


Input

5 6 8 10 1


Output

1.000000000000

Note

Consider that [a, b] denotes an interval of integers; this interval includes the boundaries. That is, <image>

In first case there are 32 suitable pairs: (1, 7), (1, 8), (1, 9), (1, 10), (2, 7), (2, 8), (2, 9), (2, 10), (3, 7), (3, 8), (3, 9), (3, 10), (4, 7), (4, 8), (4, 9), (4, 10), (7, 1), (7, 2), (7, 3), (7, 4), (8, 1), (8, 2), (8, 3), (8, 4), (9, 1), (9, 2), (9, 3), (9, 4), (10, 1), (10, 2), (10, 3), (10, 4). Total number of possible pairs is 10·10 = 100, so answer is 32 / 100.

In second case Petya always get number less than Vasya and the only lucky 7 is between this numbers, so there will be always 1 lucky number.

Solution (in PYTHON):

Solution:
import sys

def genHappies(x, n):
    if (long(x) > n):
        return [long(x)]
    return [long(x)] + genHappies(x + '4', n) + genHappies(x + '7', n)

def probability(l1, r1, l2, r2):
    l = max(l1, l2)
    r = min(r1, r2)
    if (l > r):
        return 0.0
    return float(r - l + 1) / (r1 - l1 + 1)

input = sys.stdin.readline().split(' ')
l1 = long(input[0])
r1 = long(input[1])
l2 = long(input[2])
r2 = long(input[3])
k = long(input[4])

happies = genHappies('0', max(r1, r2))
happies = sorted(happies)

res = 0.0
for i in range(len(happies)):
    if (i + k + 1 >= len(happies)):
        break
    pr1 = probability(l1, r1, happies[i] + 1, happies[i + 1])
    pr2 = probability(l2, r2, happies[i + k], happies[i + k + 1] - 1)
    res += pr1 * pr2
    pr1 = probability(l1, r1, happies[i + k], happies[i + k + 1] - 1)
    pr2 = probability(l2, r2, happies[i] + 1, happies[i + 1])
    res += pr1 * pr2
    if (k == 1):
        pr1 = probability(l1, r1, happies[i + 1], happies[i + 1])
        pr2 = probability(l2, r2, happies[i + 1], happies[i + 1])
        res -= pr1 * pr2

print(res)