array=[]
5.times do
  array << gets.chomp.to_i
end
k=gets.chomp.to_i
out = 0
5.times do |i|
  i+1.times do |j|
    if array[i] - array[j] > k
      out += 1
    end
  end
end
puts out == 0 ? 'Yay!' : ':('