///////    Basics of functional argument    ///////
#include <iostream.h>

int average(int x, int y)
{ return((x+y)/2);}

int mystery( int a, int b,  int (* fn)(int, int))
{    return( fn(a,b));  }

main()
{ int i=mystery( 8, 9, average);
        cout << "i = " << i << "\n";
}