Please solve the programming task below using a self-contained code snippet in a markdown code block.

You are given two positive integers low and high.
An integer x consisting of 2 * n digits is symmetric if the sum of the first n digits of x is equal to the sum of the last n digits of x. Numbers with an odd number of digits are never symmetric.
Return the number of symmetric integers in the range [low, high].
 
Please complete the following python code precisely:
```python
class Solution:
    def countSymmetricIntegers(self, low: int, high: int) -> int:
```