verylong add_vl(verylong ln, verylong sn) {
	/*
	 * This function calculates the sum between numbers when ln is longer than sn physically.
	 */
	int i, j, len1 = strlen(ln), len2 = strlen(sn), carry = 0, sum;

	// Allocating memory space for the result: (the size will be the longer number's size +2 for nullchar and carry)
	verylong res = (verylong)calloc(sizeof(char), (len1 + 2)), res_opt = (verylong)calloc(sizeof(char), (len1 + 1));

	for (i = len1, j = len2; i > 0; i--, j--) {
		if (j > 0) {
			sum = c2n(*(ln + -1 + i)) + c2n(*(sn + j - 1));
			*(res + i) = n2c((sum % 10) + carry);
			carry = sum / 10;
		}
		else {
			sum = c2n(*(ln + i - 1));
			*(res + i) = n2c((sum % 10) + carry);
			carry = sum / 10;
		}
	}

	*res = n2c(carry);
	*(res + len1 + 1) = '\0';

	if (*res == '0') {
		strcpy(res_opt, res + 1);
		free(res);
		return res_opt;
	}
	free(res_opt);

	return res;
}