Dequeue Using Standard Template Library

/*
TITLE:Write C++ program using STL for Dequeue (Double ended queue)
*/

#include<iostream>
#include<deque>
using namespace std;

int main()
{
int v,a;
deque<int>dq;
deque<int>::iterator it;
cout<<"1.insert from front\n";
cout<<"2.insert from back\n";
cout<<"3.delete from front\n";
cout<<"4.delete from back\n";
cout<<"5.front element\n";
cout<<"6.last element\n";
cout<<"7.size of dequeue\n";
cout<<"8.display\n";
cout<<"9.exit\n";
while(1)
{
cout<<"\nenter choice\n";
cin>>v;
switch(v)
{
case 1: cout<<"enter element\n";
cin>>a;
dq.push_front(a);
break;
case 2: cout<<"enter element\n";
cin>>a;
dq.push_back(a);
break;
case 3: a=dq.front();
dq.pop_front();
cout<<"\n"<<a<<" is deleted";
break;
case 4: a=dq.back();
dq.pop_back();
cout<<"\n"<<a<<" is deleted";
break;
case 5: a=dq.front();
cout<<"front element is "<<a<<"\n";
break;
case 6: a=dq.back();
cout<<"last element is "<<a<<"\n";
break;
case 7: cout<<"size of deque is "<<dq.size();
break;
case 8:
for(it=dq.begin();it!=dq.end();it++)
{
cout<<*it<<"\t";
}
break;
case 9:
return 0;
}
}
}