Program reading ROOT and print file and directory name and size

#include <stdio.h>
#include <dos.h>
#include <memory.h>
#include <stdlib.h>
#include <string.h>

struct BOOT {  //for FAT16
    char jmp[3];
    char OEM[8];
    int bytes_per_sector;
    char sectors_per_cluster;
    int reserved;
    char FAT_cnt;
    int ROOT_size;
    int total_sectors;
    char media;
    int FAT_size;
    int sectors_per_track;
    int head_cnt;
    long hidden_sectors;
    long total_sectors_long;
    char unknown[3];
    long serial;
    char volume[11];
    char FAT_type[8];
    char loader[448];
    char mark[2];
};

struct ROOT {
    char name[8];
    char ext[3];
    char attr;
    char reserved[10];
    char time[2];
    char date[2];
    int first_cluster;
    long size;
};

void main()
{

    int drive = 3; //A=0, B=1, C=2, D=3 ...

    //Reading boot sector from disk D
    BOOT boot;

    int res = absread(drive, 1, 0, &boot);
    if(res != 0){
        printf("Cannot read boot sector\n");
        return;
    }
    int i;
    unsigned int *fat = (unsigned int *)malloc (boot.FAT_size * boot.bytes_per_sector);
    if (fat == NULL) {
        printf("Not enough memory\n");
        return;
    }
    res = absread(drive, boot.FAT_size, boot.reserved, fat);
    int free_count = 0;
    unsigned int n = 5;
    unsigned int cur = n;
    //Reading ROOT from disk D
    printf("\n\n");
    printf("Reading ROOT information:\n");
    printf("------------------------\n");

    int num_byte = boot.ROOT_size * 32;//sizeof(ROOT)

    ROOT *root = (ROOT *)malloc(num_byte);
    if(root == NULL) return;

    int num_sector = num_byte / boot.bytes_per_sector;
    int root_begin = boot.reserved + boot.FAT_size * boot.FAT_cnt;

    res = absread(drive, num_sector, root_begin, (void *)root);
    if(res != 0){
        printf("\n Cannot read ROOT\n");
        return;
    }
    //Printing first 3 items of root
    printf("3 first items of root:\n");
    for(i = 0; i < 3; i++){
        if(root[i].name[0] == ' ') continue;
        for(int j = 0; j < 8 && root[i].name[j] != ' '; j++)
            printf("%c", root[i].name[j]);
        printf("\t");
        printf("%d \t %ld\n", root[i].first_cluster, root[i].size);
    }

    free(root);
    free(fat);

    getchar();
}