Create two classes `Alpha` and `Beta`, each with private data. Use a friend function to calculate and display the sum of their private data.

#include <iostream>
using namespace std;

class Beta;   // Forward declaration

// Class Alpha
class Alpha {
private:
    int a;
public:
    void input() {
        cout << "Enter value for Alpha: ";
        cin >> a;
    }
    // Declare friend function
    friend void sum(Alpha, Beta);
};

// Class Beta
class Beta {
private:
    int b;
public:
    void input() {
        cout << "Enter value for Beta: ";
        cin >> b;
    }
    // Declare friend function
    friend void sum(Alpha, Beta);
};

// Friend function definition
void sum(Alpha objA, Beta objB) {
    int total = objA.a + objB.b;
    cout << "Sum of Alpha and Beta = " << total << endl;
}

// Main function
int main() {
    Alpha x;
    Beta y;

    x.input();
    y.input();

    // Call friend function
    sum(x, y);

    return 0;
}