#!/usr/bin/python3
import fileinput
# import re

files = {}
subdirs = {}
size = {}
pwd = []
inls = False

def docmd(line):
	global files, subdirs, size, pwd, inls
	if line == '$ cd /':
		pwd = []
	elif line == '$ cd ..':
		pwd = pwd[:len(pwd)-1]
	elif line.startswith('$ cd'):
		pwd.append(line[5:])
	elif line.startswith('$ ls'):
		inls = True

for line in fileinput.input():
	line = line.rstrip()
	if inls:
		dir = '/' + '/'.join(pwd)
		if line.startswith('$ '):
			inls = False
			docmd(line)
			continue
		elif line.startswith('dir '):
			if dir not in subdirs:
				subdirs[dir] = []
			subdirs[dir].append(line[4:])
		else:
			(s, f) = line.split(' ')
			if dir not in files:
				files[dir] = []
			files[dir].append(f)
			size[dir + '/' + f] = int(s)
	else:
		docmd(line)

dirsize = {}
def getsize(dir):
	if dir.startswith('//'):
		dir = dir[1:]
	if dir in dirsize:
		return dirsize[dir]
	total = 0
	if dir in files:
		for f in files[dir]:
			total += size[dir + '/' + f]
	if dir in subdirs:
		for d in subdirs[dir]:
			total += getsize(dir + '/' + d)
	dirsize[dir] = total
	return total

getsize('/')

free = 70000000 - dirsize['/']
need = 30000000
smallest = dirsize['/']

for d in dirsize:
	if free + dirsize[d] >= need:
		if dirsize[d] < smallest:
			smallest = dirsize[d]

print(smallest)