use strict;
use warnings;
use List::Util qw(any);
sub diff {
	my @diff;
	for my $i (0 .. $#_-1) {
		push @diff, $_[$i+1] - $_[$i];
	}
	@diff;
}
sub extrapolate {
	my @diffs = (\@_);
	while (any { $_ != 0 } @{$diffs[0]}) {
		unshift @diffs, [diff(@{$diffs[0]})];
	}
	push @{$diffs[0]}, 0;
	for (1 .. $#diffs) {
		push @{$diffs[$_]}, $diffs[$_-1]->[-1] + $diffs[$_]->[-1];
	}
	$diffs[-1]->[-1];
}
my $sum = 0;
while (<>) {
	chomp;
	my @history = split(/ /);
	$sum += extrapolate(@history);
}
print $sum, "\n";