Vivacognita, competition “Theme of the Month”

Project Vivacognita

competition “Theme of the Month”

http://vivacognita.org/_/viva-math/monthly-problem/

Concrete theme: http://vivacognita.org/_/viva-math/monthly-problem/%d1%82%d0%b5%d0%bc%d0%b0-%d0%bd%d0%b0-%d1%84%d0%b5%d0%b2%d1%80%d1%83%d0%b0%d1%80%d0%b8-2015-r35