diff --git a/du5/program.c b/du5/program.c
new file mode 100644
index 0000000..52531c1
--- /dev/null
+++ b/du5/program.c
@@ -0,0 +1,160 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <string.h>
+#include <ctype.h>
+
+typedef struct Node {
+    int is_answer;
+    char *text;
+    struct Node *yes;
+    struct Node *no;
+} Node;
+
+// portable strdup replacement
+static char *my_strdup(const char *s) {
+    if (!s) return NULL;
+    size_t l = strlen(s) + 1;
+    char *p = malloc(l);
+    if (!p) return NULL;
+    memcpy(p, s, l);
+    return p;
+}
+
+// getline prototype (POSIX); declaring to avoid implicit declaration warnings
+ssize_t getline(char **__lineptr, size_t *__n, FILE *__stream);
+
+static char *trim_newline(char *s) {
+    if (!s) return s;
+    size_t len = strlen(s);
+    while (len > 0 && (s[len-1] == '\n' || s[len-1] == '\r')) {
+        s[--len] = '\0';
+    }
+    return s;
+}
+
+static char *ltrim(char *s) {
+    while (*s && isspace((unsigned char)*s)) s++;
+    return s;
+}
+
+Node *parse_node(char **lines, int n, int *idx, int *err) {
+    if (*idx >= n) { *err = 1; return NULL; }
+    char *line = lines[*idx];
+    (*idx)++;
+    if (line[0] == '*') {
+        // answer node
+        char *txt = line + 1;
+        txt = ltrim(txt);
+        Node *node = malloc(sizeof(Node));
+        if (!node) { *err = 1; return NULL; }
+        node->is_answer = 1;
+        node->text = my_strdup(txt);
+        node->yes = node->no = NULL;
+        return node;
+    } else {
+        // question node
+    Node *node = malloc(sizeof(Node));
+        if (!node) { *err = 1; return NULL; }
+        node->is_answer = 0;
+    node->text = my_strdup(line);
+        node->yes = parse_node(lines, n, idx, err);
+        if (*err) { free(node->text); free(node); return NULL; }
+        node->no = parse_node(lines, n, idx, err);
+        if (*err) { // free subtree? skip deep frees for brevity
+            free(node->text); free(node); return NULL;
+        }
+        return node;
+    }
+}
+
+int count_answers(Node *root) {
+    if (!root) return 0;
+    if (root->is_answer) return 1;
+    return count_answers(root->yes) + count_answers(root->no);
+}
+
+void free_tree(Node *root) {
+    if (!root) return;
+    free_tree(root->yes);
+    free_tree(root->no);
+    free(root->text);
+    free(root);
+}
+
+int main(void) {
+    // Read lines until an empty line (or EOF)
+    char *line = NULL;
+    size_t cap = 0;
+    ssize_t len;
+    char **lines = NULL;
+    int lines_count = 0;
+
+    while ((len = getline(&line, &cap, stdin)) != -1) {
+        trim_newline(line);
+        // stop at blank line
+        if (line[0] == '\0') break;
+        // store a copy
+    char *copy = my_strdup(line);
+        if (!copy) { fprintf(stderr, "Chyba pri alokácii pamäte\n"); return 1; }
+        lines = realloc(lines, sizeof(char*) * (lines_count + 1));
+        if (!lines) { fprintf(stderr, "Chyba pri alokácii pamäte\n"); return 1; }
+        lines[lines_count++] = copy;
+    }
+    free(line);
+
+    if (lines_count == 0) {
+        printf("Chyba pri načítaní bázy pravidiel\n");
+        return 0;
+    }
+
+    int idx = 0;
+    int err = 0;
+    Node *root = parse_node(lines, lines_count, &idx, &err);
+    if (err || root == NULL || idx != lines_count) {
+        printf("Chyba pri načítaní bázy pravidiel\n");
+        for (int i = 0; i < lines_count; ++i) free(lines[i]);
+        free(lines);
+        if (root) free_tree(root);
+        return 0;
+    }
+
+    int leaves = count_answers(root);
+    // print number of goods (answers)
+    printf("%d\n", leaves);
+
+    // interactive session: use 'a' for áno (yes) and 'n' for nie (no)
+    Node *cur = root;
+    char buf[128];
+    while (cur) {
+        if (cur->is_answer) {
+            // print answer and exit
+            printf("Odpoveď: %s\n", cur->text);
+            break;
+        }
+        // question
+        printf("%s\n", cur->text);
+        if (!fgets(buf, sizeof(buf), stdin)) {
+            // EOF or error
+            printf("Nesprávny vstup\n");
+            break;
+        }
+        // skip whitespace and take first non-space char
+        char *p = buf;
+        while (*p && isspace((unsigned char)*p)) p++;
+        char c = *p;
+        if (c == 'a' || c == 'A') {
+            cur = cur->yes;
+        } else if (c == 'n' || c == 'N') {
+            cur = cur->no;
+        } else {
+            printf("Nesprávny vstup\n");
+            break;
+        }
+    }
+
+    free_tree(root);
+    for (int i = 0; i < lines_count; ++i) free(lines[i]);
+    free(lines);
+    return 0;
+}
\ No newline at end of file