Friend Function demo

nclude <iostream>
using namespace std;

int add(int a, int b);

int main()
{
    int a, b;
    cin >> a >> b;
    cout << add(a, b) << endl;
    return 0;
}

int add(int a, int b)
{
    return a + b;
}

A:

You can use a lambda function to do this