CPP Inheritance

#include <iostream>
#include <string>
using namespace std;
class Gammal_Tech_member{
private:
-int day,month,year;
public:
-bool setDate(int d,int m,int y){
--if(d>=1&&d<=31)
---day=d;
--else
---return false;
--if(m>=1&&m<=12)
---month=m;
--else
---return false;
--if(y>=2020)
---year=y;
--else
---return false;
--return true;
-}
-int getDay(){
--return day;
-}
-int getMonth(){
--return month;
-}
-int getYear(){
--return year;
-}
-void print(){
--cout<<day<<"/"<<month<<"/"<<year<<endl;
-}
};
class yearly_member:public Gammal_Tech_member{
public:
-void operator ++(){
--setDate(getDay(),getMonth(),getYear()+1);
-}
};
class monthly_member:public Gammal_Tech_member{
public:
-void operator ++(){
--if(getMonth()==12)
---setDate(getDay(),1,getYear()+1);
--else
---setDate(getDay(),getMonth()+1,getYear());
-}
};
int main() {
-monthly_member Aly;
-yearly_member Nader;
-Aly.setDate(1,12,2021);
-Nader.setDate(1,11,2021);
-Aly.print();
-Nader.print();
-++Aly;
-++Nader;
-Aly.print();
-Nader.print();
}