PROGRAMMING:Intersection of two ordered linked list sequences
Given two non descending linked list sequences S1 and S2, the function is designed to construct a new linked list S3 of the intersection of S1 and S2.
###Input format:
The input is divided into two lines. In each line, a non descending sequence composed of several positive integers is given. The end of the sequence is represented by $$- 1 $$($- 1 $$does not belong to this sequence). The numbers are separated by spaces.
###Output format:
Output the intersection sequence of two input sequences in one line, the numbers are separated by spaces, and there should be no extra spaces at the end; If the new linked list is empty, output 'null'.
###Input example:
```in
1 2 5 -1
2 4 5 8 10 -1
```
###Output example:
```out
2 5
```
answer：If there is no answer, please comment
###Input format:
The input is divided into two lines. In each line, a non descending sequence composed of several positive integers is given. The end of the sequence is represented by $$- 1 $$($- 1 $$does not belong to this sequence). The numbers are separated by spaces.
###Output format:
Output the intersection sequence of two input sequences in one line, the numbers are separated by spaces, and there should be no extra spaces at the end; If the new linked list is empty, output 'null'.
###Input example:
```in
1 2 5 -1
2 4 5 8 10 -1
```
###Output example:
```out
2 5
```
answer：If there is no answer, please comment