print((function (f, s, k)
	local h = {}
	f(h,{2,3,5,7,11,13},{4,6,8,9,10,12})
	return s:format(h[k]~=nil and h[k]/36 or 0)
end)(function (h, p, c)
	for _,i in ipairs(p) do for _,j in ipairs(c) do
		local t=i*j if h[t]==nil then h[t]=0 end h[t]=h[t]+1
	end end
end, "%.15f", tonumber(io.stdin:read("*l"))))