Two strings `X` and `Y` are similar if we can swap two letters (in different positions) of `X`, so that it equals `Y`.

For example, `"tars"` and `"rats"` are similar (swapping at positions `0` and `2`), and `"rats"` and `"arts"` are similar, but `"star"` is not similar to `"tars"`, `"rats"`, or `"arts"`.

Together, these form two connected groups by similarity: `{"tars", "rats", "arts"}` and `{"star"}`. Notice that `"tars"` and `"arts"`are in the same group even though they are not similar. Formally, each group is such that a word is in the group if and only if it is similar to at least one other word in the group.

We are given a list `A` of unique strings. Every string in `A` is an anagram of every other string in `A`. How many groups are there?

Example 1:

Note:

1. `A.length <= 2000`
2. `A[i].length <= 1000`
3. `A.length * A[i].length <= 20000`
4. All words in `A` consist of lowercase letters only.
5. All words in `A` have the same length and are anagrams of each other.
6. The judging time limit has been increased for this question.