class Solution {
    public ListNode mergeInBetween(ListNode list1, int a, int b, ListNode list2) {
        ListNode head=list1;
        int diff=b-a;
        while(a-- > 1){
            list1=list1.next;
        }
        ListNode move=list1.next;
        list1.next=list2;
        while(diff-- >= 0){
            move=move.next;
        }
        while(list2.next!=null){
            list2=list2.next;
        }
        list2.next=move;
        
        return head;
    }
}