public class TreeNode {
	int val;
	TreeNode left;
	TreeNode right;
	TreeNode(int x) { val = x; }
}

public class Solution {
	public int maxDepth(TreeNode root) {
		int depth = 1;
		if (root.left != null)
			depth = Math.max(depth, maxDepth(root.left) + 1);
		if (root.right != null)
			depth = Math.max(depth, maxDepth(root.right) + 1);
		return depth;
    }
}