Overloading of operator+ in subclass

I have this code that makes a list of employee where there are also some manager, the differences between a normal employee and a manager is that a manager can get a Bonus that must be added to his salary, but this sum must be done from an overloading of operator +, so these are the header files where you can find: clas Employee, subclass Manager, class Node, class LinkedList and Main class.

Employee

#ifndef EMPLOYEE_H
#define EMPLOYEE_H
#include<string>

using namespace std;

class Employee
{
  private:
    string name;
    int salary;

public:
    Employee(string n, int s){
        name = n;
        salary = s;
    }
    virtual ~Employee() {}
    string getName(){
        return name;
    }
    int getSalary(){
        return salary;
    }
    virtual void PrintInfo(){
        cout << "'" << getName() << "'" << "--" << getSalary() << endl;
    }
    void setSalary(int n){
        this->salary = n;
    }
};

class Manager:public Employee
{
  private:
    int bonus;

public:
    Manager(string name,int salary,int bonus): Employee(name, salary){
        this->bonus = bonus;
    }
    virtual ~Manager() {}
    int getBonus(){
        return bonus;
    }
    void PrintInfo(){
        int salaryTot;
        salaryTot = getSalary() + getBonus();
        cout << "'" << getName() << "'" << " -- " << getSalary() << " -- " << getBonus() <<  " -- " << salaryTot << endl;            
    }
};

#endif // EMPLOYEE_H

--Node

#ifndef NODO_H
#define NODO_H
#include"Employee.h"

class Nodo
{
  private:
    Nodo *Next; // int next
    Employee *data; // data

  public:
    Nodo():Next{nullptr}{};
    virtual ~Nodo() {
        delete data;
    }
    Nodo *SetNext(Nodo *ptr){
        Next = ptr;
        return Next;
    }
    Nodo *getNext(){
        return Next;
    }
    void SetEmployee(Employee *data){
        this->data = data; 
    }
    Employee *getEmployee(){
        return data;
    }
};

#endif // NODO_H

--LinkedList

#ifndef LLIST_H
#define LLIST_H
#include "Employee.h"
#include "Nodo.h"

class LinkedList{
private:
    Nodo *First;
    Nodo *Last;
public:
    LinkedList():First(nullptr), Last(nullptr){}
    ~LinkedList();
    void addNodo(Employee *tmp);
    Nodo *getFirst(){
        return First;
    }
    Nodo *getLast(){
        return Last;
    }
};

void LinkedList::addNodo(Employee *data){
    Nodo *tmp = new Nodo();
    tmp->SetEmployee(data);
    if(!First){
        First = tmp;
        Last = tmp;
    }
    else
        Last = Last->SetNext(tmp);
} 

LinkedList::~LinkedList(){
    Nodo *tmp = getFirst();
    while(tmp){
         Nodo *del = tmp;
         tmp = tmp->getNext();
         delete del;
    }
}

#endif // LLIST_H

--Main

#include <iostream>
#include <string>
#include"LinkedList.h"

using namespace std;

int main(){
    Employee *emp1=new Employee(string("Adam Sandler"),1000);
    Employee *emp2=new Employee(string("Lionel Messi"),2000);
    Employee *emp3=new Manager(string("Cristiano Ronaldo"),2000,2000);
    Employee *emp4=new Manager(string("Ed Sheeran"),3000,3000);

    //Create an Employee List
    LinkedList list;
    list.addNodo(emp1);
    list.addNodo(emp2);
    list.addNodo(emp3);
    list.addNodo(emp4);

    //Print of every employee info
    Nodo *stmp;
    int sommaTot = 0;
    stmp = list.getFirst();
    while (stmp != nullptr){
        stmp->getEmployee()->PrintInfo();
        sommaTot = sommaTot + stmp->getEmployee()->getSalary();
        stmp = stmp->getNext();
    }
    cout << "The total is: " << sommaTot << endl;
return 0;
}

Now, what should I do to implement the + operator overload to make the sum of all the salaries (including those of the employees who are managers where I must also add the bonus)?

The output of this code is:

'Adam Sandler'--1000
'Lionel Messi'--2000
'Cristiano Ronaldo' -- 2000 -- 2000 -- 4000
'Ed Sheeran' -- 3000 -- 3000 -- 6000
The total is: 8000

But the total should be = 13000.