
antennas = []
5.times do
    line = gets.chomp.to_i
    antennas.push(line)
end

k = gets.chomp.to_i

flag = true
for i in 0..3
    for j in (i + 1)..4
        flag = false if antennas[j] - antennas[i] > k
    end
end

if flag
    puts "Yay!"
else
    puts ":("
end
