arr = []
5.times do
  arr.push gets.strip.to_i
end
k = gets.strip.to_i
r = 'Yay!'
4.downto(1) do |i|
  i.downto(0) do |j|
    if (arr[i] - arr[j]) > k
      r = ':('
      break
    end
  end
end
puts r