CF375A Divisible by Seven

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^{6} $ characters.

Print a number in the decimal notation without leading zeroes — the result of the permutation. If it is impossible to rearrange the digits of the number $ a $ in the required manner, print 0.