multilevel inheritance with protector

#include<iostream>
#include<math.h>
using namespace std;
class people

{
    int age;
public:
    people(int x)
    {

        age=x;

    }
    void display()
    {
        cout<<"age is "<<age<<endl;
    }
};

class student:public people
{
    float cgpa;
public:
    student(int a,float b):people(a)
    {
        cgpa=b;
    }
    void display()
    {
        people::display();
        cout<<"cgpa is "<<cgpa<<endl;
    }
};
class employee:public people
{
    protected:
    int salary;
public:
    employee(int b,int s):people(b)
    {
        salary=s;
    }
    void display()
    {
        student::display;
        cout<<"salary is "<<salary<<endl;

    }
};
class excute_student: public student,public employee
{

public:
    excute_student(int a,float b,int s):student(a,b),employee(a,s)
    {}

    void dispaly()
    {

        student::display();
        cout<<"salary:"<<salary<<endl;

    }
};

int main()
{
    people p1(26);
    p1.display();
    student s1(18,3.45);
   s1.display();
    employee e1(36,19000);
    e1.display();
    excute_student es1(23,3.65,6900);
    es1.dispaly();
}