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

#define MAXN 1000000000000
#define NRUMAX 10000000

long long ru[NRUMAX];
int nru = 0;

int comp(const void *a, const void *b)
{
	long long x = *(long long*)a;
	long long y = *(long long*)b;

	if (x < y)
		return -1;
	else if (x > y)
		return 1;
	else 
		return 0;
}

int main()
{
	long long sum_repunit = 1; /* 1 is a strong repunit */
	for (int base = 2; base < 1000000; base++) {
		long long repunit = 1 + base;
		long long nb = base;
		while (1) {
			nb *= base;
			repunit += nb;
			if (repunit >= MAXN)
				break;
			assert(nru < NRUMAX);
			ru[nru] = repunit;
			nru++;
		}
	}

	qsort(ru, nru, sizeof(long long), comp);

	printf("Find %d strong repunits.\n", nru + 1);
	for (int i = 0; i < nru; i++) {
		if (i > 0 && ru[i] == ru[i-1])
			continue;
		sum_repunit += ru[i];
	}
	printf("Their sum is %lld\n", sum_repunit);
}