#include <iostream>
#include <string>

int x = 3;

const int& GetX() {
    return x;
}

void DoStuff() {
    x = 5;
}

int main() {
  const auto& myConstX = GetX();
  std::cout << "x: " << myConstX << "\n"; // prints 3
  DoStuff();
  std::cout << "x: " << myConstX << "\n"; // prints 5
}