N = gets.chomp.to_i
p = gets.chomp.split(" ").map(&:to_i)
#s = p.inject(:*)                                                               
if p.include?(0)
  s = 0
else
  s = 1
  p.each do |i|
    s*=i
  end
end

if s==0
  p 0
elsif s%9 ==0
  p 9
else
  p s%9
end