def solve() -> None:
    disk_map: list[int] = list(map(int, get_string(as_list=True)))
    disk_map_with_dots: list[int] = []
    curr_id: int = 0
    heaps_free_space: list[list[int]] = [[] for _ in range(10)]  # one heapq per size
    # in the heapq we store idx first free space
    for i in range(len(disk_map)):
        if i % 2 == 0:
            # it's a file
            disk_map_with_dots += [curr_id for _ in range(disk_map[i])]
            curr_id += 1
        else:
            # it's free space
            if disk_map[i] > 0:
                heapq.heappush(heaps_free_space[disk_map[i]], len(disk_map_with_dots))
                for _ in range(disk_map[i]):
                    disk_map_with_dots.append(-1)

    i: int = len(disk_map_with_dots) - 1
    while i >= 0:
        if disk_map_with_dots[i] != -1:
            file_id: int = disk_map_with_dots[i]
            file_width: int = 0
            while i >= 0 and disk_map_with_dots[i] == file_id:
                i -= 1
                file_width += 1
            # swap with left most
            smallest_idx: int = 10**18
            best_width: int = 0
            for width in range(file_width, 10):
                if heaps_free_space[width]:
                    if smallest_idx > heaps_free_space[width][0]:
                        smallest_idx = heaps_free_space[width][0]
                        best_width = width
            if smallest_idx != 10**18 and smallest_idx <= i:
                for j in range(file_width):
                    disk_map_with_dots[smallest_idx + j] = file_id
                    disk_map_with_dots[i + j + 1] = -1
                heapq.heappop(heaps_free_space[best_width])
                if best_width - file_width > 0:
                    heapq.heappush(heaps_free_space[best_width - file_width], smallest_idx + file_width)
        else:
            i -= 1

    ans: int = 0
    for i in range(len(disk_map_with_dots)):
        if disk_map_with_dots[i] != -1:
            ans += disk_map_with_dots[i] * i
    print(ans)


if __name__ == "__main__":
    import time
    start_time = time.time()
    solve()
    print("--- %s seconds ---" % (time.time() - start_time))