B

//Second question in OOP Labs ( B )
#include"iostream"
#include"string"
using namespace std;
class secondClass;
class firstClass
{
private:
    int a[4];
public:
    void set()
    {
        int i;
        for (i = 0; i < 4; i++)
        {
            cout << "Enter Data : ";
            cin >> a[i];
        }
    }
    friend void check(firstClass, secondClass);
};
class secondClass
{
private:
    int x;
public:
    void set()
    {
        cout << "Enter Number : "; cin >> x;
    }
    friend void check(firstClass, secondClass);
};
void  check(firstClass f, secondClass s)
{
    if (s.x == 1)
        f.a[4] += 10;
    else if (s.x == 0)
        f.a[4] -= 10;
}
int main()
{
    firstClass f;
    secondClass s;
    f.set();
    s.set();
    check(f, s);
}