Start with a deque: 
     3 4 7 8 

Use an insert_iterator: 
     3 4 5 6 7 8 

Use a front_inserter: 
     1 1 1 1 3 4 5 6 7 8 

Use a back_inserter: 
     1 1 1 1 3 4 5 6 7 8 1 1 1 1