function Node(val) {
    this.val = val;
    this.left = null;
    this.right = null;
}

function commonParent(root, val1, val2) {
    if (root == null) return null;

    if (root.val == val1 || root.val == val2) return root;

    let left = commonParent(root.left, val1, val2);
    let right = commonParent(root.right, val1, val2);

    if (left != null && right != null) return root;
    else if (left == null) return right;
    else return left;
}

function createNode(val) {
    return new Node(val);
}

let n2 = createNode(2);
let n4 = createNode(4);
let n5 = createNode(5);
let n8 = createNode(8);
let n9 = createNode(9);
let n10 = createNode(10);
let n11 = createNode(11);

n2.left = n4;
n2.right = n5;
n4.left = n8;
n4.right = n9;
n5.left = n10;
n5.right = n11;

const commonNode = commonParent(n2, 8, 11);
console.log(commonNode && commonNode.val);