program Main
implicit none
    integer a, b, c, d, e, k
    read *, a, b, c, d, e, k
    if (b-a > k .or. c-b > k .or. d-c > k .or. e-d > k) then
        print '(a)', ':('
    else
        print '(a)', 'Yay!'
    endif
end program Main