is_Balanced (BINARY TREE) - Is sample output wrong?

Q- To check if a given tree is BST or not?
The tree given in sample input is not a binary tree clearly
10
20 50
30 40 60 73

but output shows its true.

if its correct, where i am wrong?
https://ide.codingblocks.com/s/63669

MARK IT AS RESOLVED, The question is not bst but for only binary tree, i misunderstood.