typedef struct ListNode listNode;

struct ListNode *getIntersectionNode(struct ListNode *headA, struct ListNode *headB) {
    listNode *a = headA, *b = headB;
    while (a != b && (a->next != NULL || b->next != NULL)) {
        if (a->next == NULL) {
            a = headB;
        }
        else {
            a = a->next;
        }
        if (b->next == NULL) {
            b = headA;
        }
        else {
            b = b->next;
        }
    }

    if (a != b) {
        return NULL;
    }
    else {
        return a;
    }
}