In a country consisting of 2017 cities there are two way flights between some pairs of cities so that any two cities are connected by a flight route (direct or consisting of several flights). Find the minimal possible value of k for which for any such flight arrangement one can declare k cities special so that from any city (special or not special) there is a direct flight to at least one special city.
Correct Solutions by,
- Toshihiro Shimizu Kawasaki, Japan
- Serdar Hojayev Dashoguz, Turkmenistan
- Mehmet Ali Yıldırım, Florya Final Anadolu Lisesi, İstanbul
- Hasan Zubeyr Demir, Özel Çaglayan Fen Lisesi, Ankara
- Tomas Jurik Kosice, Slovakia
- İlker Can Çicek, İstanbul Lisesi
- Kayra Uygun, Ankara Fen Lisesi
- Onur Korkmaz, İzmir Fen Lisesi