class Calc0239
  def initialize(args)
    args = args.map { |l| l.chomp.split(/\s+/) }
    @n = args.shift.first.to_i
    @as = args.transpose
  end

  def run
    rens = []
    @as.each_with_index do |r, i|
      rens << i + 1 if (r - ['-']).all? { |a| a == 'nyanpass' }
    end
    if rens.empty? || rens.size >= 2
      -1
    else
      rens.first
    end
  end
end

puts Calc0239.new(STDIN.readlines).run if __FILE__ == $0