Sorry, can't understand.

```
Input:
[0]
Output:
0
Expected:
1
```

Why?

The depth of a node is the number of edges from the root to the node. The height of a node is the number of edges from the node to the deepest leaf. The height of a tree is a height of the root.

There is root only. How depth can be 1?

Where am I wrong?

Update:

I see in task

```
The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.
```

But it is not depth, it's height.