Longest consecutive sequence in Binary tree (Function Problem)

Given a Binary Tree find the length of the longest path which comprises of nodes with consecutive values in increasing order. Every node is considered as a path of length 1. Input:

The first line of the input contains a single integer T denoting the number of test cases. For each test a root node is given to the longestConsecutivefunction. The only input to the function is the root of the binary Tree. Output:

For each test case output in a single line, find the length of the longest path of the binary tree.
If no such sequence is possible return -1.

Constraints:

1<=T<=50
1<=N<=50 Example:

Input:

2
2
1 2 L 1 3 R
5
10 20 L 10 30 R 20 40 L 20 60 R 30 90 L

Output:

2
-1

Explanation: Test case 1:

1

/ \

2 3

For the above test case the longest sequence is : 1 2

Test case 2:

10

/ \

20 30

/ \ /

40 60 90

For the above test case no sequence is possible: -1

Note:The Input/Ouput format and Example given are used for system's internal purpose, and should be used by a user for Expected Output only. As it is a function problem, hence a user should not read any input from stdin/console. The task is to complete the function specified, and not to write the full code.