one day Vasya come blackboard write n distinct integer 1 n order circle then draw arcs join pair integers ab ab immediate neighbor circle number c с immediate neighbor b c immediate neighbor as easily deduce end Vasya draw 2n arcsfor example number write circle order 12345 clockwise direction arc join pair integer 12 23 34 45 51 13 24 35 41 52much time pass number wipe blackboard long ago recently Vasya find piece paper 2n write pair integer join arcs board Vasya ask find order number circle pair