void recursive_itoa(int n, char s[])
{
	long long int pn = 0;
	int sign = 1;
	char digit;
	static int i = 0;

	if (n < 0)
	{
		pn = -n;
		sign = -1;
		s[i++] = '-';
	}
	else
		pn = n;

	if (pn / 10 > 0)
	{
		digit = (pn % 10) - '0'; //digit 3 2
		pn /= 10;	//123 12
		recursive_itoa(pn, s);
	}
	else
		digit = (pn % 10) - '0'; // 1 1

	s[i++] = digit;
}