#include 
    using namespace std;
    void swap(int &p, int &q);
    int main()
    {
        int p = 5, q = 10;
        swap(p, q);
        cout << " In main " << p << q;
        return 0;
    }
    void swap(int &p, int &q)
    {
        int temp;
        temp = p;
        p = q;
        q = temp;
        cout << "In swap " << p << q;
    }