#include <iostream>

using namespace std;

int f(int &x)
{
	x = x+1;
	return x;
}

int main()
{
	int xx = 0;
	cout << f(xx) << endl;
	cout << xx << endl;

	int yy = 7;
	cout << f(yy) << endl;
	cout << yy << endl;
}