Given an integer n, add a dot (".") as the thousands separator and return it in string format.
Example 1:
Input: n = 987
Output: "987"
Example 2:
Input: n = 1234
Output: "1.234"
Example 3:
Input: n = 123456789
Output: "123.456.789"
Example 4:
Input: n = 0
Output: "0"
Constraints:
0 <= n < 2^31
class Solution:
    def thousandSeparator(self, n: int) -> str:
        
        n = list(str(n))
        if len(n) > 3:
            for i in range(len(n)-3,0,-3):
                n.insert(i, '.')
        return ''.join(n)
            

class Solution:
    def thousandSeparator(self, n: int) -> str:
        
        n = list(str(n))
        if len(n) > 3:
            for i in range(len(n)-3,0,-3):
                n.insert(i, '.')
        return ''.join(n)
            
