How to find greatest of 3 numbers using getters and setters?

CODE

How to find greatest of 3 numbers using getters and setters?

//Write a program to find greatest of 3 numbers using getters and setters…

#include<iostream>

using namespace std;

class gr

{

    int a,b,c,max;

    public:

    void setValue(int a1,int b1,int c1)

    {

        a=a1;

        b=b1;

        c=c1;

    }

    void pro()

    {

        if(a>b)

        {

            if(a>c)

                max=a;

            else

                max=c;

        }

        else

            if(b>c)

                max=b;

            else

                max=c;

    }

    int getValue()

    {

        return max;

    }

};

int main()

{

    gr obj;

    int a1,b1,c1,max;

    cout<<"\n enter 3 numbers:\n";

    cin>>a1>>b1>>c1;

    obj.setValue(a1,b1,c1);

    obj.pro();

    max=obj.getValue();

    cout<<"\n maximum value="<<max;

}

Output:

enter 3 numbers:

24

78

59

 maximum value=78