The count-and-say sequence is a sequence of digit strings defined by the recursive formula:

- `countAndSay(1) = "1"`
- `countAndSay(n)` is the way you would "say" the digit string from `countAndSay(n-1)`, which is then converted into a different digit string.

To determine how you "say" a digit string, split it into the minimal number of groups so that each group is a contiguous section all of the same character. Then for each group, say the number of characters, then say the character. To convert the saying into a digit string, replace the counts with a number and concatenate every saying.

For example, the saying and conversion for digit string `"3322251"`:

Given a positive integer `n`, return the `nth` term of the count-and-say sequence.

Example 1:

    Input: n = 1
    Output: "1"
    Explanation: This is the base case.

Example 2:

    Input: n = 4
    Output: "1211"
    Explanation:
    countAndSay(1) = "1"
    countAndSay(2) = say "1" = one 1 = "11"
    countAndSay(3) = say "11" = two 1's = "21"
    countAndSay(4) = say "21" = one 2 + one 1 = "12" + "11" = "1211"

Constraints:

- `1 <= n <= 30`