public class ListNode {
    int val;
    ListNode next = null;

    ListNode(int val) {
        this.val = val;
    }
}*/
public class Solution {
    public ListNode Merge(ListNode list1,ListNode list2) {
        ListNode head = new ListNode(0);
        ListNode tmp = head;
        while(list1 != null && list2 != null){
            if(list1.val >= list2.val){
                tmp.next = list2;
                tmp = tmp.next;
                list2 = list2.next;
            }else if(list1.val < list2.val){
                tmp.next = list1;
                tmp = tmp.next;
                list1 = list1.next;
            }
        }
        if(list2 != null){
            tmp.next = list2;  
        }
        if(list1 != null){
            tmp.next = list1;
        }
        return head.next;
    }
}