int ucnvrf(char *);

int ucnvrf(char *s)
{
	int i, sum = 0;
	static char m[] = {2,4,8,5,10,9,7,3,6,11};

	for (i = 0; i < 9; i++)
		sum += (*s++ - '0') * m[i];
	sum %= m[i];
	return sum % 10 - (*s - '0');
}