count-commas-in-range-ii

You are given an integer n.

Return the total number of commas used when writing all integers from [1, n] (inclusive) in standard number formatting.

In standard formatting:

• A comma is inserted after every three digits from the right.


• Numbers with fewer than 4 digits contain no commas.

Example 1:

Input: n = 1002

Output: 3

Explanation:

The numbers "1,000", "1,001", and "1,002" each contain one comma, giving a total of 3.

Example 2:

Input: n = 998

Output: 0

Explanation:

​​​​​​​All numbers from 1 to 998 have fewer than four digits. Therefore, no commas are used.

Constraints:

• 1 <= n <= 1015