Struct variable in class in heap and usage of smart pointer

How can I use smart pointer here?

#include <iostream>
using namespace std;
struct node
{
    char data;
    node *next;
};

class linked_list
{
private:
    node *head,*tail,*tmp;
public:
    linked_list()
    {
        head = nullptr;
        tail = nullptr;
    }

    void add_node()
    {
        tmp = new node();
        cin>> tmp->data;
        tmp->next = nullptr;

        if(head == nullptr)
        {
            head = tmp;
            tail = tmp;
        }
        else
        {
            tail->next = tmp;
            tail = tail->next;
        }
    }
    void print()
    {
        tmp=head;
        while(tmp!=nullptr)
        {
            cout<<tmp->data;
            tmp=tmp->next;
            cout<<endl;
        }       
    }
};
int main()
{
    linked_list a;
    a.add_node();
    a.add_node();
    a.add_node();
    a.add_node();
    a.print();
    return 0;
}

How can I change first line of code of add_note function to use smart pointer and not have to worry about new/delete later. What changes are required? Should I have to change multiple lines of code? If so,then where?