with open('input.text', 'r') as file:
    data = file.read()

drive: list[int] = []

is_file = True
f_id = 0
for c in data:

    if is_file:
        drive.extend([f_id] * int(c))
        f_id += 1
    else:
        drive.extend([-1] * int(c))

    is_file = not is_file

def print_drive(drive: list[int]) -> None:

    for i in drive:
        if i != -1:
            print(i, end='')
        else:
            print('.', end='')

    print()

def compress_drive(drive: list[int]) -> list[int]:
    max_f_id: int = max(drive)
    while max_f_id != 0:

        file_index: int = drive.index(max_f_id)
        size: int = drive.count(max_f_id)

        free_size = 0
        free_index = None
        found_block = False
        for i, id in enumerate(drive):

            if i >= file_index:
                break

            if id == -1:
                free_size += 1
                if not free_index:
                    free_index = i
            else:
                free_size = 0
                free_index = None

            if free_size >= size:
                found_block = True
                break

        if found_block:
            drive[file_index:file_index + size] = [-1] * size
            drive[free_index:free_index + size] = [max_f_id] * size

        max_f_id -= 1

    return drive

def checksum(drive: list[int]) -> int:
    s = 0
    for i, id in enumerate(drive):
        if id != -1:
            s += i * id

    return s

# print_drive(drive)
# print_drive(compress_drive(drive))

drive = compress_drive(drive)
print(checksum(drive))