function findMergeNode(headA, headB) {
   let current1 = headA;
    let current2 = headB;

    let length1 = 0;
    let length2 = 0;

    while (current1) {
        length1++;
        current1 = current1.next;
    }

    while (current2) {
        length2++;
        current2 = current2.next;
    }

    current1 = headA;
    current2 = headB;

    if (length1 > length2) {
        for (let i = 0; i < length1 - length2; i++) {
            current1 = current1.next;
        }
    } else if (length2 > length1) {
        for (let i = 0; i < length2 - length1; i++) {
            current2 = current2.next;
        }
    }

    while (current1 && current2) {
        if (current1 === current2) {
            return current1.data; 
        }
        current1 = current1.next;
        current2 = current2.next;
    }

    return null; 
}