#include<stdio.h>
int main(){
	int a = 2;

	void double_a(){
		a *= 2;
	}

	printf("a = %d\n", a);
	double_a();
	printf("a = %d\n", a);
	double_a();
	double_a();
	double_a();
	printf("a = %d\n", a);
	return 0;
}