# require "template"
lib C
  fun strtoll(s : UInt8*, p : UInt8**, b : Int32) : Int64
end

class String
  def to_i64
    C.strtoll(self, nil, 10)
  end
end

n = read_line.to_i
a = read_line.split.map(&.to_i)
one = a.chunk { |i| i }.select { |b| b[0] == 1 }.map(&.[1].size).to_a
puts n.to_i64 * -~n // 2 - one.sum { |m|
  m.to_i64 * -~m // 2
}