1. In a magical country, some cities are connected by roads in such a way that from any city, you can get to any other city, possibly through some other cities. No two cities are directly connected by more than one road.

We will call a road special if, when it is closed, it becomes impossible to travel from some city to some other city. It is known that there are 25 roads in the country, 20 of which are special. How many cities can there be in the country? If there are several correct answers, list them separated by commas or semicolons.
Answer: $24,25\|25,24\| 24 ; 25 \| 25 ; 24$