text: str = open("input.txt", "r").read()

_value: int = 0 

lines = text.splitlines()

def get_difference(values: [int]):
	lst = []
	for i in range(0, len(values) - 1):
		lst.append(values[i + 1] - values[i])
	return lst

def get_next(derives: [[int]]):
	value = 0
	for values in derives[::-1]:
		if (len(values) == 0):
			continue
		value = values[-1] + value
	return value

for line in lines:
	values = list(map(int, line.split()))
	derives: [[int]] = [values]
	lst = values
	while True:
		lst = get_difference(lst)
		derives.append(lst)
		if (lst.count(0) == len(lst)):
			break
	_value += get_next(derives)

print(_value)