Inaccessible error in inherited function

[Abhishek kore]

THis is my small program i am getting
error CPP 46: 'result::putdata()'is not accessible

#include<iostream.h>
#include<conio.h>

class stud
{
protected:
int rno;
public:
void getdata()
{
cout<<"enter ur roll no";
cin>>rno;
}
void display()
{
cout<<"\n Roll no is "<<rno;
}
};
class marks:public stud
{
protected:
int m1,m2;
public:
void setvalue()
{
cout<<" enter the marks of 2 subjects";
cin>>m1>>m2;
}
};
class result:public marks
{
void putdata()
{
int total=m1+m2;
setvalue();
cout<<"\n total is "<<total;
}
};
void main()
{
clrscr();
result a;
a.getdata();
a.setvalue();
a.display();
a.putdata();

getch();
}

[Stewbond]

result::putdata() is private. Make it public.