class Solution {
public:
ListNode* deleteDuplicates(ListNode* head) {
ListNode* temp = new ListNode(0,head);
ListNode* prev=temp;
while(head!=NULL){
if(head->next!=NULL && head->val == head->next->val){
while(head->next!=NULL && head->val == head->next->val){
head=head->next;
}
prev->next = head->next;
}
else{
prev = prev->next;
}
head=head->next;
}
return temp->next;
}
};