A digit string is good if the digits (0-indexed) at even indices are even and the digits at odd indices are prime (`2`, `3`, `5`, or `7`).

- For example, `"2582"` is good because the digits (`2` and `8`) at even positions are even and the digits (`5` and `2`) at odd positions are prime. However, `"3245"` is not good because `3` is at an even index but is not even.

Given an integer `n`, return the total number of good digit strings of length `n`. Since the answer may be large, return it modulo `109 + 7`.

A digit string is a string consisting of digits `0` through `9` that may contain leading zeros.

Example 1:

    Input: n = 1
    Output: 5
    Explanation: The good numbers of length 1 are "0", "2", "4", "6", "8".

Example 2:

    Input: n = 4
    Output: 400

Example 3:

    Input: n = 50
    Output: 564908303

Constraints:

- `1 <= n <= 1015`