- import java.util.*; 
-   
- class deque{ 
-     private static final int Size = 200000; 
-     int start, end; 
-     int [] folder = new int[Size] ; 
-   
-     deque(){ 
-         start = end = Size/2; 
-     } 
-     void push_front(int var){ 
-         folder[--start] = var; 
-     } 
-     void push_back(int var){ 
-         folder[end++] = var; 
-     } 
-     void pop_front(){ 
-     	System- . out- . println(- folder [- start ++]);
 
-     } 
-     void pop_back(){ 
-     	System- . out- . println(- folder [--- end ]);
 
-     } 
-     void front(){ 
-     	System- . out- . println(- folder [- start ]);
 
-     } 
-     void back(){ 
-     	System- . out- . println(- folder [- end -1]);
 
-     } 
-     void size(){ 
-     	System- . out- . println(- end -- start );
 
-     } 
-     void clear(){ 
-     	start = end = Size/2; 
-     } 
- }; 
-   
- class Main 
- { 
- 	{ 
- 		Scanner scan  = new-  Scanner (System- . in);
- 		deque deq = new deque(); 
-   
- 		while (scan.hasNext()){ 
- 			S = scan.next(); 
- 			if (S.equals("push_front"))	deq.push_front(scan.nextInt()); 
- 			else	if (S.equals("push_back"))	deq.push_back(scan.nextInt()); 
- 			else	if (S.equals("pop_front"))	deq.pop_front(); 
- 			else	if (S.equals("pop_back"))	deq.pop_back(); 
- 			else	if (S.equals("front"))	deq.front(); 
- 			else	if (S.equals("back"))	deq.back(); 
- 			else	if (S.equals("size"))	deq.size(); 
- 			else	if (S.equals("clear"))	deq.clear(); 
- 			else	if (S.equals("exit")){ 
- 				} 
- 		} 
- 	} 
- } 
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