Given a positive integer `k`, you need to find the length of the smallest positive integer `n` such that `n` is divisible by `k`, and `n` only contains the digit `1`.

Return the length of `n`. If there is no such `n`, return -1.

Note: `n` may not fit in a 64-bit signed integer.

Example 1:

    Input: k = 1
    Output: 1
    Explanation: The smallest answer is n = 1, which has length 1.

Example 2:

    Input: k = 2
    Output: -1
    Explanation: There is no such positive integer n divisible by 2.

Example 3:

    Input: k = 3
    Output: 3
    Explanation: The smallest answer is n = 111, which has length 3.

Constraints:

- `1 <= k <= 105`