Let's say there is an encoding scheme where integer 1 encodes character 'A', integer 2 encodes character 'B' and so on till integer 26 which encodes character 'Z'. With this encoding scheme, write a program to count all possible decodings of a given digit sequence.

For example, if the digit sequence is "12" then there are two possible decodings for this - One of them is 'AB' when we decode 1 as 'A' and 2 as 'B'. Now we can also decode this digit sequence "12" as 'L' when we decode digits 1 and 2 taken together as an integer 12.

Similarly, for digit sequence "1223" there are five possible decodings.

1, 2, 2, 3 - ABBC

1, 2, 23 - ABW

1, 22, 3 - AVC

12, 2, 3 - LBC

12, 23 - LW

For digit sequence "1234" there are three possible decodings.

1, 2, 3, 4 - ABCD

1, 23, 4 - AWD

12, 3, 4 - LBD

Note that because integer 34 does not have any valid decoding, we cannot decode "1234" as 1,2,34 or as 12,34 where digits 3 and 4 are decoded together(as an integer 34) to some character.

Few assumptions that we can make here -

1. Number of possible decodings for an empty sequence = 0.

2. There would be no 0's at the very beginning of digit sequence. That means, no digit sequence would start from digit 0.

3. There would be no two or more consecutive 0's in the digit sequence.

4. The digit sequence would be formed by only using digits from 0-9.