Your task is to implement a double linked list.

Write a program which performs the following operations:

• insert x: insert an element with key x into the front of the list
• delete x: delete the first element which has the key of x from the list
• deleteFirst: delete the first element from the list
• deleteLast: delete the last element from the list

Input

The input is given in the following format:

n
command₁
command₂
...
command_n

In the first line, the number of operations n is given. In the following n lines, the above mentioned operations are given in the following format:

• insert x
• delete x
• deleteFirst
• deleteLast

Output

Print all the element (key) in the list after the given operations. Two consequtive keys should be separated by a single space.

Constraints

• The number of operations ≤ 2,000,000
• The number of delete operations ≤ 20
• 0 ≤ value of a key ≤ 10⁹
• the number of elements in the list does not exceed 10⁶

Sample Input 1

7
insert 5
insert 2
insert 3
insert 1
delete 3
insert 6
delete 5

Sample Output 1

6 1 2

Sample Input 2

9
insert 5
insert 2
insert 3
insert 1
delete 3
insert 6
delete 5
deleteFirst
deleteLast

Sample Output 2

1

 1     #include <iostream>  
 2     #include <cstdio>  
 3     #include <cstring>  
 4     #include <cstdlib>  
 5     using namespace std;  
 6       
 7     struct Node{  
 8       int key;  
 9       Node *prev;  
10       Node *next;  
11     };  
12       
13     Node *head;  
14       
15     Node *listSearch(int key){  
16       Node *cur = head->next;  
17       while(cur != head && cur->key != key){  
18         cur = cur->next;  
19       }  
20       return cur;  
21     }  
22       
23     void init(){  
24       head = new Node;  
25       head->prev = head;  
26       head->next = head;  
27     }  
28       
29     void printlist(){  
30       Node *cur = head->next;  
31       int isf = 0;  
32       while(1){  
33         if(cur == head)break;  
34         if(isf++ > 0)printf(" ");  
35         printf("%d",cur->key);  
36         cur = cur->next;  
37       }  
38       printf("\n");  
39     }  
40       
41     void insert(int key){  
42       Node *x = new Node;  
43       x->key = key;  
44       x->next = head->next;  
45       head->next->prev = x;  
46       head->next = x;  
47       x->prev = head;  
48     }  
49       
50     void deleteNode(Node *t){  
51       if(t == head)return;  
52       t->prev->next = t->next;  
53       t->next->prev = t->prev;  
54       free(t);  
55     }  
56       
57     void deleteFirst(){  
58       deleteNode(head->next);  
59     }  
60       
61     void deleteLast(){  
62       deleteNode(head->prev);  
63     }  
64       
65     void deletekey(int key){  
66       deleteNode(listSearch(key));  
67     }  
68       
69     int main(){  
70       int key,n,i;  
71       char com[20];  
72       scanf("%d",&n);  
73       init();  
74       for(i = 0;i < n; i++){  
75         scanf("%s%d",com,&key);  
76         if(com[0] == ‘i‘){insert(key);}  
77         else if(com[0] == ‘d‘){  
78           if(strlen(com) > 6){  
79             if(com[6] == ‘F‘)deleteFirst();  
80             else if(com[6] == ‘L‘)deleteLast();  
81           }  
82           else{  
83             deletekey(key);  
84           }        
85         }  
86       }  
87       printlist();  
88       return 0;  
89     }