Binary Trees1-Sum Of Nodes

For a given Binary Tree of integers, find and return the sum of all the nodes data.
Example:
                        10
                      /      \
                    20      30
                   /    \
                 40    50

When we sum up all the nodes data together, [10, 20, 30, 40 50] we get 150. Hence, the output will be 150.
 Input Format:
The first and the only line of input will contain the nodes data, all separated by a single space. Since -1 is used as an indication whether the left or right node data exist for root, it will not be a part of the node data.
Output Format:
The first and the only line of output prints the sum of all the nodes data present in the binary tree.
Note:
You are not required to print anything explicitly. It has already been taken care of.
Constraints:
1 <= N <= 10^6
Where N is the total number of nodes in the binary tree.

Time Limit: 1 sec
Sample Input 1:
2 3 4 6 -1 -1 -1 -1 -1
Sample Output 1:
 15
Sample Input 2:
1 2 3 4 5 6 7 -1 -1 -1 -1 -1 -1 -1 -1
Sample Output 2:
 28
 
 *******************************************Code*******************************************
 
 public static int getSum(BinaryTreeNode<Integer> root) {
		
		if(root == null) {
		return 0;
		}
		int leftSum = getSum(root.left);
		int rightSum = getSum(root.right);
		return leftSum + rightSum + root.data;
	}