Sum of nodes in binary tree whose grandparents exists

Grandchild node of binary tree whose parents and grandparents exist. For example.

Example 1
         4   
        /  \                          
       /    \    
      12     7    
     / \      \               
    2   3      1
       / \    / 
      6   8  5
     /        
    9                        
-------------------
Here node 
node key   parent  grandparents
   2        12         4
   3        12         4
   6        3         12
   8        3         12  
   9        6         3 
   1        7         4  
   5        1         7 
--------------------------
  34
--------------------------

Example 2
-----------

         4   
        /  \                          
       /    \    
      12     7    
     / \                    
    2   3      
       / \     
      6   8   
     /        
    9                        
-------------------
Here node 
node key   parent  grandparents
   2        12         4
   3        12         4
   6        3         12
   8        3         12  
   9        6         3    
--------------------------
  28
--------------------------

Here given code implementation process.

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