#!/usr/bin/env python3

import sys

input_file = sys.argv[1]

with open(input_file) as fd:
    lines = [line.rstrip() for line in fd.readlines()]

line = lines[0]

disk: list[int | None] = list()
# position, size
index: list[tuple[int, int]] = list()

fileno = 0
isfile = True
for char in line:
    n = int(char)
    if isfile:
        index.append((len(disk), n))
        disk += [fileno] * n
        fileno += 1
    else:
        disk += [None] * n
    isfile = not isfile

beg = 0
end = len(disk) - 1


def print_disk() -> None:
    return
    print("".join(str(c) if c is not None else "." for c in disk))


print_disk()

for pos, size in index[::-1]:
    hole_start = None
    for c, cid in enumerate(disk + [-1]):
        if c > pos + size:
            break
        if cid is None:
            if hole_start is None:
                hole_start = c
        else:
            if hole_start is not None:
                hole_size = c - hole_start
                if hole_size < size:
                    hole_start = None
                    continue
                for i in range(size):
                    disk[hole_start + i] = disk[pos + i]
                    disk[pos + i] = None
                print_disk()
                break

checksum = 0
for c, cid in enumerate(disk):
    if cid is not None:
        checksum += c * cid

print(checksum)