#!/usr/bin/env python
from common import Folder, parse


def folders_big_enough(folder: Folder, threshold: int) -> list[Folder]:
    if folder.size < threshold:
        return []
    else:
        folder_list = [folder]
        for child in filter(lambda x: type(x) is Folder, folder.children):
            folder_list += folders_big_enough(child, threshold)
        return folder_list


def solve(folder: Folder) -> int:
    threshold = 30000000 - (70000000 - folder.size)
    return min(sorted(folders_big_enough(folder, threshold))).size


def main():
    print(solve(parse("input")))


if __name__ == "__main__":
    main()