You are given an array of `n` strings `strs`, all of the same length.

We may choose any deletion indices, and we delete all the characters in those indices for each string.

For example, if we have `strs = ["abcdef","uvwxyz"]` and deletion indices `{0, 2, 3}`, then the final array after deletions is `["bef", "vyz"]`.

Suppose we chose a set of deletion indices `answer` such that after deletions, the final array has every string (row) in lexicographic order. (i.e., `(strs[0][0] <= strs[0][1] <= ... <= strs[0][strs[0].length - 1])`, and `(strs[1][0] <= strs[1][1] <= ... <= strs[1][strs[1].length - 1])`, and so on). Return the minimum possible value of `answer.length`.

Example 1:

    Input: strs = ["babca","bbazb"]
    Output: 3
    Explanation: After deleting columns 0, 1, and 4, the final array is strs = ["bc", "az"].
    Both these rows are individually in lexicographic order (ie. strs[0][0] <= strs[0][1] and strs[1][0] <= strs[1][1]).
    Note that strs[0] > strs[1] - the array strs is not necessarily in lexicographic order.

Example 2:

    Input: strs = ["edcba"]
    Output: 4
    Explanation: If we delete less than 4 columns, the only row will not be lexicographically sorted.

Example 3:

    Input: strs = ["ghi","def","abc"]
    Output: 0
    Explanation: All rows are already lexicographically sorted.

Constraints:

- `n == strs.length`
- `1 <= n <= 100`
- `1 <= strs[i].length <= 100`
- `strs[i]` consists of lowercase English letters.