
a = [ ]

a.push gets.to_i
a.push gets.to_i
a.push gets.to_i
a.push gets.to_i
a.push gets.to_i

k = gets.to_i

catch :break do
  for i in 0...a.size
    for j in (i+1)...a.size
      unless a[j] - a[i] <= k
        puts ':('
        throw :break
      end
    end
  end
  puts 'Yay!'
end
