#include<stdio.h>
#include<stdlib.h>
#include<string.h>


#define MAX_NUM 1000000


int split_digits(int* digits, int num)
{
	int len = 0;
	while (num > 0) {
		len++;
		digits[len-1] = num % 10;
		num /= 10;
	}

	return len;
}


int main(int argc, char** argv)
{
	int digits[7] = {0};
	int len;
	int digit = 0, i = 0;
	int prod = 1, num = 1;

	len = split_digits(digits, num);

	while (digit < MAX_NUM) {
		if (digit == 0 || digit == 9 || digit == 99 || digit == 999
			|| digit == 9999 || digit == 99999 || digit == 999999)
			/* Need to step through the array backward */
			prod *= digits[len-1-i];

		digit++;
		i++;
		if (i == len) {
			/* refill digits and reset i */
			num++;
			i = 0;
			len = split_digits(digits, num);
		}
	}

	printf("The solution is %d\n", prod);
	return 0;
}