You have number *a*, whose decimal representation quite luckily contains digits 1, 6, 8, 9. Rearrange the digits in its decimal representation so that the resulting number will be divisible by 7.

Number *a* doesn't contain any leading zeroes and contains digits 1, 6, 8, 9 (it also can contain another digits). The resulting number also mustn't contain any leading zeroes.
The first line contains positive integer *a* in the decimal record. It is guaranteed that the record of number *a* contains digits: 1, 6, 8, 9. Number *a* doesn't contain any leading zeroes. The decimal representation of number *a* contains at least 4 and at most 10<sup class="upper-index">6</sup> characters.
from itertools import permutations

t, r = [0, 1, 4, 6, 5, 2], {i: 0 for i in '0123456789'}
for i in input(): r[i] += 1
for i in '1689': r[i] -= 1

s = a = b = 0
for i in '9876543210':
    a, b = b, (b + r[i]) % 6
    s += int(i) * (t[b]	- t[a])
d = pow(10, b, 7)

for q in permutations('1689'):
    q = ''.join(q)
    if (s + d * int(q)) % 7 == 0:
        print(q + ''.join(i * r[i] for i in '0123456789'))
        break