2160\. Minimum Sum of Four Digit Number After Splitting Digits

Easy

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`
