#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <assert.h>
#include <signal.h>
void seq(int n)
{
	for(int i = 2; i <= n; i++)
		write(STDOUT_FILENO, &i, sizeof i);
	exit(0);
}
void filtre(int prime)
{
	while(1){
		int n;
		ssize_t nb_read = read(STDIN_FILENO, &n, sizeof n);
		if (nb_read <= 0)
			break;
		if ((n%prime) != 0)
			write(STDOUT_FILENO, &n, sizeof n);

	}
	exit(0);
}
int main(int argc, char *argv[])
{

	pid_t p;
	int fd[2];
	struct sigaction sa = {0};

	sa.sa_handler = SIG_IGN;
	sigaction(SIGCHLD, &sa, NULL);

	int N = strtol(argv[1], NULL, 0);
	assert(pipe(fd) == 0);

	p = fork();

	if (p == 0){
		close(fd[0]);
		dup2(fd[1],STDOUT_FILENO);
		close(fd[1]);
		seq(N);
	}
	close(fd[1]);
	dup2(fd[0],STDIN_FILENO);
	close(fd[0]);

	while(1){
		int prime;
		int fdd[2];
		ssize_t nb_read = read(STDIN_FILENO, &prime, sizeof prime);
		if (nb_read <= 0)
			break;
		printf("%d\n",prime);
		assert(pipe(fdd) == 0);
		p = fork();
		if (p == 0){
			close(fdd[0]);
			dup2(fdd[1],STDOUT_FILENO);
			close(fdd[1]);
			filtre(prime);
		}
		close(fdd[1]);
		dup2(fdd[0], STDIN_FILENO);
		close(fdd[0]);

	}



	return 0;
}