#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

int main(int ac, char **av)
{
	char *cmd;

	int nb = atoi(av[1]);
	if (nb == 423) {
		cmd = strdup("/bin/sh");
		gid_t gid = getegid();
		uid_t uid = geteuid();
		setresgid(gid, gid, gid);
		setresuid(uid, uid, uid);
		execv("/bin/sh", &cmd);
	} else {
		fwrite("No !\n", 1, 5, (FILE *)stderr);
	}
	return 0;
}