I recently came across a OI camp problem which I've been stuck on for some time now. Could anyone help me? Here's the problem statement:

Bytel is a mobile telephony potentate. Each employee has been issued a company phone, the memory of which holds the numbers of some of his co-workers (all of them have their own number in their phones as well). Due to dynamic growth of their operations the board of directors intends to move company headquaters to new office buildings. It has been decided — in order to boost work efficiency — that every pair of employees working in different buildings should know (reciprocally) each others phone number i.e. their phone ought to hold necessary phone numbers.

Simultaneously, the board has decided to rent as many office buildings as possible to ensure good working conditions. Help the board of Bytel to plan the number of office buildings and their size in accordance with the aforementioned requirements.

I've thought about this for this but haven't made much progress. I initially thought about working with connected components and perhaps doing some dsu but could not think of anything more. Could anyone help?