void queue :: circle()
{
    node *now= front;
    int Pleft= 0, c= 0, index= 0;
    node *temp= now, *ptr= now;
    while(temp->next != now)
    {
        
        Pleft+= temp->petrol;
        //cout<<"pleft: "<<Pleft<<" distance: "<<temp->dist<<endl;
        if(Pleft < temp->dist)
        {
            temp= ptr->next;
            now= temp;
            ptr= temp;
            Pleft= 0;
            c= 0;
        }
        else
        {
            c++;
            if(c == 1)
            {
                ptr= temp;
                index= temp->petrol;
            }   
            Pleft-= temp->dist;
           // cout<<"in else pleft: "<<Pleft<<endl;
            temp= temp->next;
        }
    }
    int flag= 0;
    while(front->next != front)
    {
        if(index == front->petrol)
        {
            cout<<flag<<endl;
            break;
        }
        flag++;
        front= front->next;
    }
}