#!/usr/bin/env python
# 2023 - Advent Of Code 9 - part 2

# file = 'input_example.txt'
file = 'input.txt'


def all_zeroes(lst):
    for i in lst:
        if i != 0:
            return False
    return True


# pylint: disable=consider-using-with
input_lines = [line.strip('\n') for line in open(file, encoding="utf-8")]
res = 0

for line in input_lines:
    sequence = [int(x) for x in line.split()]
    print(sequence)
    diffs_list = [sequence]
    while not all_zeroes(sequence):
        diffs = [sequence[s+1] - sequence[s] for s in range(0, len(sequence)-1)]
        diffs_list.append(diffs)
        sequence = diffs

    # print(diffs_list)

    for seq in range(len(diffs_list)-1, -1, -1):
        if seq == len(diffs_list)-1:
            diffs_list[seq].insert(0, 0)
        else:
            d = diffs_list[seq][0] - diffs_list[seq + 1][0]
            # print(f'{diffs_list[seq][0]} - {diffs_list[seq + 1][0]} = {d}')
            diffs_list[seq].insert(0, d)
        # print(f'diffs: {diffs_list[seq]}')
    res += d

    print()

print(res)