a = (gets).to_i
b = (gets).to_i
c = (gets).to_i
d = (gets).to_i
e = (gets).to_i
k = (gets).to_i

antenas = [a,b,c,d,e]

chk = true
antenas.combination(2) do |p,q|
    if (p-q).abs > k then
        chk = false
        break
    end
end

if chk then
    puts "Yay!"
else
    puts ":("
end