Binary Trees2-Minimum and Maximum in the Binary Tree

For a given a Binary Tree of type integer, find and return the minimum and the maximum data values.
Return the output as an object of Pair class, which is already created.
Note:
All the node data will be unique and hence there will always exist a minimum and maximum node data.
Input Format:
The first and the only line of input will contain the node 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 only line of output prints two integers denoting the minimum and the maximum data values respectively. A single line will separate them both.
Constraints:
2 <= N <= 10^5
Where N is the total number of nodes in the binary tree.

Time Limit: 1 sec
Sample Input 1:
8 3 10 1 6 -1 14 -1 -1 4 7 13 -1 -1 -1 -1 -1 -1 -1
Sample Output 1:
1 14
Sample Input 2:
10 20 60 -1 -1 3 50 -1 -1 -1 -1 
Sample Output 2:
3 60

******************************************Solution**********************************************
private static Pair<Integer,Integer> maxMin=new Pair<Integer,Integer>(Integer.MAX_VALUE, Integer.MIN_VALUE);

	public static Pair<Integer, Integer> getMinAndMax(BinaryTreeNode<Integer> root) {
		
		getMinAndMaxHelper(root);
		return maxMin;
	}
	
	private static void getMinAndMaxHelper(BinaryTreeNode<Integer> root)
	{
		if(root==null)
			return;
		int rootData=root.data;
		int maxVal=maxMin.maximum;
		if(rootData>maxVal)
		{
			maxMin.maximum=root.data;
		}
		int minVal=	maxMin.minimum;
		if(rootData<minVal)
		{
			maxMin.minimum=root.data;
		}
		getMinAndMax(root.left);
		getMinAndMax(root.right);
	}