d = []
5.times do
  d << gets.to_i
end

k = gets.to_i

flag = true
5.times do |i|
  5.times do |j|
    if (d[i] - d[j]).abs > k
      flag = false
    end
  end
end

if flag
  puts 'Yay!'
else
  puts ':('
end
