P = gets.chomp.chars.map(&:to_i) N = P.size single_flg = false P.reverse_each.with_index do |v, idx| if idx == 0 if (2..4).cover?(v) else puts "No" exit end elsif idx == N - 1 if single_flg if (6..7).cover?(v) else puts "No" exit end else if v == 1 else puts "No" exit end end else if single_flg if (6..7).cover?(v) else puts "No" exit end else if (3..5).cover?(v) # next elsif (7..8).cover?(v) single_flg = true else puts "No" exit end end end end puts "Yes"