using System;

public class Node {

    public char data;

    public Node left;

    public Node right;

    public Node(char data) {

        this.data = data;

        this.left = null;

        this.right = null;

    }

}

public class Program

{

    static Node LCA(Node root, Node p, Node q) {

        if(root == null)

            return null;

        if(root == p || root == q)

            return root;

        Node left = LCA(root.left, p, q);

        Node right = LCA(root.right, p, q);

        if(left != null && right != null)

            return root;

        else

            return (left != null ? left : right);

    }   

    public static void Main()

    {

        Node root = new Node('a');

        root.left = new Node('b');

        root.right = new Node('c');

        root.left.left = new Node('d');

        root.left.right = new Node('e');

        root.left.left.left = new Node('h');

        root.left.left.right = new Node('i');

        root.right.left = new Node('f');

        root.right.left.left = new Node('j');

        root.right.left.right = new Node('k');

        root.right.right = new Node('g');

        root.right.right.right = new Node('l');

        root.right.right.right.left = new Node('m');

        root.right.right.right.right = new Node('n');

        Console.Write(LCA(root, root.left, root.left.right).data);

    }

}