print((function (f, s)
	return string.format("%.2f", f(s))
end)(function (s)
	local t,a = 0,{}
    for e in s:gmatch("%d+") do table.insert(a,tonumber(e)) end
	table.sort(a)
	for i=2,5 do t=t+a[i] end
	return t/4
end, io.stdin:read("*l")))