diff --git a/du5/program.c b/du5/program.c
index 14b0599..7ca54db 100644
--- a/du5/program.c
+++ b/du5/program.c
@@ -20,6 +20,7 @@ int lineCount = 0;
 int indexLine = 0;
 int nodeCount = 0;
 int answerCount = 0;
+bool isTreeBroken = false;
 
 //pomocna konstanta
 const int invalidIndex = -1;
@@ -30,6 +31,7 @@ int buildATree()
 {
     if (indexLine >= lineCount)
     {
+        isTreeBroken = true;
         return -1;
     }
 
@@ -57,6 +59,12 @@ int buildATree()
     tree[current].yes = buildATree(); // 'a' 
     tree[current].no  = buildATree(); // 'n'
 
+    //kontrola - jedna otazka musii mat dve deti (AK NIE vyhodi chybu)
+    if (tree[current].yes == -1 || tree[current].no == -1)
+    {
+        treeIsBroken = true;
+    }
+
     return current;
 }