#include <stdio.h>
#include <deque>
using namespace std;
struct process;
struct process;
struct count_to_n_data;
typedef int (*process_func)(process *p);
struct process;
struct process
{
	process_func f;
	int pc;
	void *data;
};
struct count_to_n_data
{
	int n;
	int c;
};
int count_to_three(process *p);
int count_to_n(process *p);
int main(void);
int count_to_three(process *p)
{
	switch(p->pc)
	{
	case 0:	printf("1\n");
		return 1;
	case 1:	printf("2\n");
		return 2;
	case 2:	printf("3\n");
		return 3;
	case 3:	;
	}
	return -1;
}
int count_to_n(process *p)
{
	count_to_n_data *d = (count_to_n_data *)p->data;
	switch(p->pc)
	{
	case 0:	d->c = 1;
		while(d->c <= d->n)
		{
			printf("%d\n", d->c);
			++ (d->c);
			return 1;
	case 1:		;
		}
	}
	return -1;
}
int main(void)
{
	process c3 = { count_to_three, 0 };
	while(c3.pc != -1)
	{
		c3.pc = (*c3.f)(&c3);
	}
	count_to_n_data d1, d2;
	process cn1 = { count_to_n, 0, &d1 };
	process cn2 = { count_to_n, 0, &d2 };
	d1.n = 10;
	d2.n = 15;
	deque<process *> q;
	q.push_back(&cn1);
	q.push_back(&cn2);
	while(!q.empty())
	{
		process *p = q.front();
		q.pop_front();
		int pc = (*p->f)(p);
		if(pc != -1)
		{
			p->pc = pc;
			q.push_back(p);
		}
	}
	return 0;
}