class Calc0077
  def initialize(args)
    args = args.map { |l| l.chomp.split(/\s+/) }
    @n = args.shift.first.to_i
    @as = args.shift.map(&:to_i)
  end

  def run
    (1..Math.sqrt(@as.inject(:+)).floor).map { |k|
      calc(k)
    }.min
  end

  def calc(k)
    ps = (1..k).to_a + (1..(k-1)).to_a.reverse
    ((-@as.size + 1)..0).map { |m|
      le = @as.map.with_index { |a, i|
        a - ((0...(k * 2 - 1)).include?(m + i) ? ps[m + i] : 0)
      }
      le.select(&:positive?).inject(:+) || 0
    }.min
  end
end

puts Calc0077.new(STDIN.readlines).run if __FILE__ == $0