3 4 1 3 2 3 1 2 1 2
0 0 1 3
The land lot for the construction will look in the following way:
We can choose a subset of roads in three ways:
In the first and the second ways you can choose one path, for example, 1 - 2 - 3 - 1. In the first case you can choose one path 1 - 2 - 1.