In an undirected graph, each node has a *“level”* – a distance to the root (start) node. One of the special properties that could be extracted is that if there is a connection between two nodes of the same level, then there is also a cycle of odd length in the graph, which in turn gives us more properties about the structure.

The input file **DATA4.txt** will contain 5 sets of input: A single positive integer 1 ≤ `N` < 50, followed by `N` lines describing the graph. Each of those lines is two integers IDs of nodes, separated by a space. Node IDs are positive integers less than 100. The root (start) node has ID 1.

The output file **OUT4.txt** will contain 5 lines, each being the integer count of how many pairs of nodes have a connection, such that the shortest path length from 1 to each node in the pair is equal.

```
3
1 2
3 2
1 3
10
1 2
1 3
2 3
2 4
3 5
3 6
4 5
5 6
4 7
5 7
```

```
1
3
```