#include <sys/types.h>
#include <unistd.h>
#include <stdio.h>
#include <sys/stat.h>
#include <fcntl.h>

typedef struct Node
{
    int32_t key;
    int32_t left_ind;
    int32_t right_ind;
} Node;

int
read_node(int fd, int n, Node *nd)
{
    return ((lseek(fd, sizeof(Node) * n, SEEK_SET) != -1) &&
            (read(fd, nd, sizeof(*nd)) == sizeof(*nd)));
}

int
rec(int fd, int n)
{
    Node nd;
    if (!read_node(fd, n, &nd)) {
        return 0;
    }

    if (nd.right_ind != 0) {
        rec(fd, nd.right_ind);
    }

    printf("%d\n", nd.key);

    if (nd.left_ind != 0) {
        rec(fd, nd.left_ind);
    }

    return 1;
}

int
main(int argc, char *argv[])
{
    int fd = -1;
    if ((fd = open(argv[1], O_RDONLY)) == -1 ||
            !rec(fd, 0)) {
        fprintf(stderr, "Error error\n");
        return 1;
    }

    close(fd);
    return 0;
}