I have a function for which the complexity raise by the square ten of the exponent of the number.
Ex:
+-----+----------+
|Input|Complexity|
+-----+----------+
|0 | 1 |
|10 | 2 |
|100 | 3 |
|123 | 3 |
|1001 | 4 |
|9999 | 4 |
|10000| 5 |
|99999| 5 |
+-----+----------+
How to express its complexity in big O notation ?