##templete
lst = []
5.times do |i|
  lst[i] = gets.chomp.to_i
end

k = gets.chomp.to_i

for i in 0..3 do
  for j in i+1..4 do
    if lst[j] - lst[i] > k
      puts ":("
      exit 0
    end
  end
end

puts "Yay!"
