Team Selection Optimization netbectis: k$)$ If there are two students With powar $x$ and $Y$ in subject $Z,$ the powns of the team in that hibgect wil be $x+Y.$

menove Nstuetents and want to choose from them a team that can solve all the probtems of the competition and be composed of as few students as possible, It in mandatory that you choose a successive subgroup while selecting a team.

Your task is to find the smallest number of students in the team to be able to win. If it is not possible to determine the answer print $-1$