Given two linked lists sorted in ascending order. Merge them in-place and return head of the merged list.   For example, if first list is 10->20->30 and second list is 15->17, then the result list should be 10->15->17->20->30.

It is strongly recommended to do merging in-place using O(1) extra space.

Input:
You have to complete the method which takes 2 argument: the head of the first linked list  and the head of second linked list. You should not read any input from stdin/console. There are multiple test cases. For each test case, this method will be called individually.

Output:
Your function should return a pointer to the list obtained by merging the two sorted linked list passed as argument.

Constraints:
1 <=T<= 200
1 <= size of linked lists <= 1000
1 <= Data in linked list nodes <= 1000

Example:
Input:
2
4 3
5 10 15 40 
2 3 20
2 2
1 1
2 4 

Output:

2 3 5 10 15 20 40 
1 1 2 4 

** For More Input/Output Examples Use 'Expected Output' option **