#include <iostream>
using namespace std;

int powerOf2(int x) {
  x = x*x;
  return x;
}

int powerOf2Ref(int &x) {
  x = x*x;
  return x;
}

int powerOf2Ptr(int *x) {
  *x = (*x)*(*x);
  return *x;
}

int main() {
  int a = 5, b;
  b = powerOf2(a);
  cout << "a: " << a <<", b: " << b << endl;
  a = 5;
  b = powerOf2Ref(a);
  cout << "a: " << a <<", b: " << b << endl;
  a = 5;
  b = powerOf2Ptr(&a);
  cout << "a: " << a <<", b: " << b << endl;  
}