ListNode* swapPairs(ListNode* head){

    ListNode* temp = head;
    ListNode* temp2;

    if(head->next != NULL){
        head = head->next;
        temp->next = head->next;
        head->next = temp;
    }

    while(temp != NULL){
        if(temp->next != NULL && temp->next->next != NULL){
            temp2 = temp->next;
            temp->next = temp2->next;
            temp = temp->next;
            temp2->next = temp->next;
            temp->next= temp2;
        }
        temp = temp->next;
    }

    return head;
}