#include <iostream>
#include <cstdlib>
using namespace std;

void f();   //function declaration

int main()
{
	f();
	f();
	f();

	return EXIT_SUCCESS;
}

void f()   //function definition
{
	static int n {0};   //assigned to 0 only during the first call
	++n;
	cout << "This is call number " << n << ".\n";
}