diff --git a/du6/program.c b/du6/program.c
new file mode 100644
index 0000000..6a22f88
--- /dev/null
+++ b/du6/program.c
@@ -0,0 +1,128 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define SIZE 256
+
+typedef struct tree {
+    char value[SIZE];
+    struct tree *left;
+    struct tree *right;
+} Tree;
+
+/* Odstráni koncový znak \n */
+void strip_newline(char *s) {
+    int len = strlen(s);
+    if (len > 0 && s[len-1] == '\n')
+        s[len-1] = '\0';
+}
+
+/* Rekurzívne načítanie stromu v preorder */
+Tree* read_tree() {
+    char buffer[SIZE];
+
+    if (!fgets(buffer, SIZE, stdin))
+        return NULL;
+
+    /* prázdny riadok = koniec bázy pravidiel */
+    if (strcmp(buffer, "\n") == 0)
+        return NULL;
+
+    strip_newline(buffer);
+
+    Tree *node = calloc(1, sizeof(Tree));
+    if (!node) exit(1);
+
+    strcpy(node->value, buffer);
+
+    /* Odpoveď = list */
+    if (buffer[0] == '*') {
+        return node;
+    }
+
+    /* Inak načítaj oboch potomkov */
+    node->left = read_tree();
+    if (!node->left) {
+        free(node);
+        return NULL;
+    }
+
+    node->right = read_tree();
+    if (!node->right) {
+        free(node->left);
+        free(node);
+        return NULL;
+    }
+
+    return node;
+}
+
+/* Uvoľnenie pamäte */
+void destroy_tree(Tree *t) {
+    if (!t) return;
+    destroy_tree(t->left);
+    destroy_tree(t->right);
+    free(t);
+}
+
+/* Počet listov = počet tovarov */
+int count_leaves(Tree *t) {
+    if (!t) return 0;
+    if (!t->left && !t->right)
+        return 1;
+    return count_leaves(t->left) + count_leaves(t->right);
+}
+
+/* Spustenie znalostného systému */
+void run_system(Tree *node) {
+    printf("%s\n", node->value);
+
+    /* List → koniec */
+    if (!node->left && !node->right) {
+        printf("Koniec\n");
+        return;
+    }
+
+    char c;
+    if (scanf(" %c", &c) != 1) {
+        printf("Odpovedajte 'a' pre prvu moznost alebo 'n' pre druhu moznost.\n");
+        return;
+    }
+
+    if (c == 'a') {
+        run_system(node->left);
+    } else if (c == 'n') {
+        run_system(node->right);
+    } else {
+        printf("Odpovedajte 'a' pre prvu moznost alebo 'n' pre druhu moznost.\n");
+    }
+}
+
+int main() {
+    Tree *root = read_tree();
+
+    /* Ak sa nepodarilo načítať koreň, chyba */
+    if (!root) {
+        printf("Chyba\n");
+        return 0;
+    }
+
+    /* Skontrolovať prázdny riadok po báze pravidiel */
+    char buffer[SIZE];
+    if (!fgets(buffer, SIZE, stdin) || strcmp(buffer, "\n") != 0) {
+        printf("Chyba\n");
+        destroy_tree(root);
+        return 0;
+    }
+
+    int leaves = count_leaves(root);
+
+    printf("Expert z bufetu to vie.\n");
+    printf("Pozna %d druhov ovocia a zeleniny.\n", leaves);
+    printf("Odpovedajte 'a' pre prvu moznost alebo 'n' pre druhu moznost.\n");
+
+    run_system(root);
+
+    destroy_tree(root);
+    return 0;
+}