PROGRAMMING:String connection
Realize with linked list: copy the string t to the end of the string s, return the first address of the new string, and write the main program output.
Example: (instructions in brackets)
###Input example:
```in
abc
def
```
###Output example:
```out
abcdef
```
answer：If there is no answer, please comment
Example: (instructions in brackets)
###Input example:
```in
abc
def
```
###Output example:
```out
abcdef
```
answer：If there is no answer, please comment