Elections Berland come there candidate Alice BobThe main Berland TV channel plan political debate there n people want debate spectator each person describe influence political view there kind political view support candidate kind denote 00 support Alice Bob kind denote 10 support Bob Alice kind denote 01 support candidate kind denote 11 the direction tv channel wants invite people debate the set invite spectator satisfy condition half spectator support Alice ie 2 cdot ge m number spectator support Alice m total number spectator half spectator support Bob ie 2 cdot b ge m b number spectator support Bob m total number spectator total influence spectator maximal possible help tv channel direction select nonempty set spectator tell impossible