diff --git a/du6/program.c b/du6/program.c
index d0cb707..f4e01c4 100644
--- a/du6/program.c
+++ b/du6/program.c
@@ -24,7 +24,7 @@ static TreeNode* read_tree_node() {
     }
 
     TreeNode *node = calloc(1, sizeof(TreeNode));
-    if (node == NULL) {
+    if (!node) {
         exit(1);
     }
 
@@ -37,7 +37,7 @@ static TreeNode* read_tree_node() {
     }
 
     node->yes_branch = read_tree_node();
-    node->no_branch  = read_tree_node();
+    node->no_branch = read_tree_node();
     return node;
 }
 
@@ -54,15 +54,36 @@ static int count_leafs(TreeNode *root) {
         return 0;
     }
 
-    int left_count = count_leafs(root->yes_branch);
-    int right_count = count_leafs(root->no_branch);
+    int left = count_leafs(root->yes_branch);
+    int right = count_leafs(root->no_branch);
 
     int is_leaf = 0;
     if (root->yes_branch == NULL && root->no_branch == NULL) {
         is_leaf = 1;
     }
 
-    return left_count + right_count + is_leaf;
+    return left + right + is_leaf;
+}
+
+static int validate_tree(TreeNode *root) {
+    if (root == NULL) {
+        return 0;
+    }
+
+    int is_answer = (root->text[0] == '*');
+
+    if (is_answer) {
+        if (root->yes_branch != NULL || root->no_branch != NULL) {
+            return 0;
+        }
+        return 1;
+    }
+
+    if (root->yes_branch == NULL || root->no_branch == NULL) {
+        return 0;
+    }
+
+    return validate_tree(root->yes_branch) && validate_tree(root->no_branch);
 }
 
 static void skip_empty_line() {
@@ -90,7 +111,7 @@ static void run_dialog(TreeNode *root) {
         return;
     }
 
-    char c = 0;
+    char c;
     int r = scanf(" %c", &c);
 
     if (r != 1) {
@@ -118,14 +139,15 @@ int main() {
 
     printf("Expert z bufetu to vie.\n");
 
-    if (root == NULL) {
+    if (root == NULL || !validate_tree(root)) {
         printf("Chybna databaza\n");
+        free_tree(root);
         return 0;
     }
 
-    int total_types = count_leafs(root);
+    int total = count_leafs(root);
 
-    printf("Pozna %d druhov ovocia a zeleniny.\n", total_types);
+    printf("Pozna %d druhov ovocia a zeleniny.\n", total);
     printf("Odpovedajte 'a' pre prvu moznost alebo 'n' pre druhu moznost.\n");
 
     run_dialog(root);