#!/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()

fileno = 0
isfile = True
for char in line:
    n = int(char)
    if isfile:
        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()
moving = False
while beg < end:
    if moving:
        if disk[end] is not None:
            disk[beg] = disk[end]
            disk[end] = None
            moving = False
            print_disk()
        end -= 1
    else:
        if disk[beg] is None:
            moving = True
        else:
            beg += 1

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

print(checksum)