n = read_line.to_i
a = read_line.split.map(&.to_i).reverse
s = 1
ans = 0
1.upto(n - 1) do |i|
  if a[i] == a[i - 1]
    s = i
  end
  if a[i] == 1
    ans += i - s + 1
  end
end
puts ans