#!/usr/bin/env lua
local ds = {} -- unique value
local pwd, tree, output = {}, {[ds]=0}, error
local allfolders = {tree}
--[[Walk a tree and call a function on each node]]
local function walk(dir, path, f)
	local cursor = dir
	for _,v in ipairs(path) do
		f(cursor)
		cursor = cursor[v]
	end
	f(cursor)
	return cursor
end
local commands = {}
function commands.cd(arg)
	if arg == "/" then pwd = {}
	elseif arg == ".." then table.remove(pwd)
	else table.insert(pwd, arg) end
end
function commands.ls()
	local cursor = walk(tree, pwd, function() end)
	output = function(line)
		if line:match("^dir") then
			local dirname = line:match("^dir (%w+)$")
			cursor[dirname] = {[ds]=0}
			table.insert(allfolders, cursor[dirname])
		else
			local filesize, filename = line:match("(%d+) ([%w.]+)")
			walk(tree, pwd, function(f)
				f[ds] = f[ds] + tonumber(filesize)
			end)[filename] = filesize
		end
	end

end
for line in io.lines() do
	if line:match("^%$") then --it's a command
		local line_split = {}
		line:gsub("(%S+)", function(w) table.insert(line_split,w) end)
		table.remove(line_split, 1) -- remove '$'
		-- remove command and call the appropriate function
		commands[table.remove(line_split, 1)](table.unpack(line_split))
	else output(line) end
end
local needs = 3e7 - (7e7 - tree[ds])
table.sort(allfolders, function(a,b) return a[ds] < b[ds] end)
for i = 1,#allfolders do
	if allfolders[i][ds] > needs then
		print(allfolders[i][ds])
		break
	end
end