import abc

with open('input7.txt','r') as f:
    inp = f.read().splitlines(keepends=False)

class FSObject:
    __metaclass__ = abc.ABCMeta

    def __init__(self, parent):
        self._parent = parent

    @abc.abstractmethod
    def name(self):
        pass

    @abc.abstractmethod
    def size(self):
        pass

    def fullpath(self):
        if self._parent:
            return self._parent.fullpath() + "/" + self.name()
        else:
            return self.name()


class File(FSObject):
    def __init__(self, parent, name, size):
        super(File, self).__init__(parent)
        self._name = name
        self._size = size
    
    def size(self):
        return self._size

class Directory(FSObject):
    def __init__(self, parent, name):
        super(Directory, self).__init__(parent)
        self._name = name
        self.contain = []

    def newEntry(self, obj):
        self.contain.append(obj)
    
    def size(self):
        _size = 0
        for x in self.contain:
            _size += x.size()
        return _size


location = []
rootdir = Directory(None, "")
curdir = rootdir
dirs = [rootdir]
_all = []
answer = 0
totalSpace = 70000000
requiredSpace = 30000000
opt = None

for i in inp:
    if i.startswith('$ cd'):
        target = i[5:]
        if target == '..':
            location.pop()
            dirs.pop()
            curdir = dirs[-1]
        else:
            location.append(target)
            newdir = Directory(curdir, target)
            _all.append(newdir)
            curdir.newEntry(newdir)
            dirs.append(newdir)
            curdir = newdir
    elif i.startswith('$ ls'):
        pass
    else:
        tempa, tempb = i.split(' ', 1)
        if tempa.isnumeric():
            curdir.newEntry(File(curdir, tempb, int(tempa)))

freeSpace = totalSpace - rootdir.size()
toDelete = requiredSpace - freeSpace

for i in _all:
    tempa = i.size()
    if tempa >= toDelete and ((not opt) or tempa < opt):
        opt = tempa

print(opt)