#include <iostream>
using namespace std;

int subtraction(int  a   // a is passed by value 
               ,int& b){ // b is passed by reference
  int r;
  cout << "a is " << a << endl;
  cout << "b is " << b << endl;
  r=a-b;
  a++;
  b++;
  cout << "new a is " << a << endl;   
  cout << "new b is " << b << endl;
  return (r);
}

int main (){
  int z;
  int a = 2;
  int b = 3;

  cout << endl;
  z = subtraction(a,b);
  cout << "(a-b) is " << z << endl;
  cout << "The value of a in the main program is " << a << endl;
  cout << "The value of b in the main program is " << b << endl;

  cout << endl;
  return 0;
}