antenna = []
count = 0
n = 0

5.times do
    antenna << gets.chomp.to_i
end
dis = gets.chomp.to_i

antenna.each do|a|
    antenna.each do|b|
        if a - b > dis
            count += 1
        end
    end
end

if count >= 1
    puts ":("
else
    puts "Yay!"
end