You are given a positive integer `num` consisting of exactly four digits. Split `num` into two new integers `new1` and `new2` by using the digits found in `num`. Leading zeros are allowed in `new1` and `new2`, and all the digits found in `num` must be used.

- For example, given `num = 2932`, you have the following digits: two `2`'s, one `9` and one `3`. Some of the possible pairs `[new1, new2]` are `[22, 93]`, `[23, 92]`, `[223, 9]` and `[2, 329]`.

Return the minimum possible sum of `new1` and `new2`.

Example 1:

    Input: num = 2932
    Output: 52
    Explanation: Some possible pairs [new1, new2] are [29, 23], [223, 9], etc.
    The minimum sum can be obtained by the pair [29, 23]: 29 + 23 = 52.

Example 2:

    Input: num = 4009
    Output: 13
    Explanation: Some possible pairs [new1, new2] are [0, 49], [490, 0], etc.
    The minimum sum can be obtained by the pair [4, 9]: 4 + 9 = 13.

Constraints:

- `1000 <= num <= 9999`