PROGRAMMING:Sequence traversal binary linked list
The program is designed to create the binary list of binary tree in order; Then the sequence traverses the binary tree.
###Input format:
Input a binary tree in order. The key value of each node in the binary tree is represented by characters, and there is no space between the characters. Note that the empty tree information should also be provided, and the # character is used to represent the empty tree.
###Output format:
The output sequence traverses the binary tree sequence. The sequence does not contain spaces or #.
###Input example:
```in
abc##d##e#f##
```
###Output example:
```out
abecdf
```
answer：If there is no answer, please comment
###Input format:
Input a binary tree in order. The key value of each node in the binary tree is represented by characters, and there is no space between the characters. Note that the empty tree information should also be provided, and the # character is used to represent the empty tree.
###Output format:
The output sequence traverses the binary tree sequence. The sequence does not contain spaces or #.
###Input example:
```in
abc##d##e#f##
```
###Output example:
```out
abecdf
```
answer：If there is no answer, please comment