Resulting code from the naive approach

#include <cstdio>
#include <vector>

using namespace std;

// PLACE THE OUTPUT OF THE GENERATOR CODE HERE.

int main() {
    int n, k;

    scanf("%d", &n);

    // Retrieving the number of unlucky numbers up to N.
    for (k = 0; k < ans.size(); k++) {
        if (ans[k] > n) {
            break;
        }
    }

    // Printing all the unlucky numbers up to N in ascending order.
    printf("%d\n", k);

    for (int i = 0; i < k; i++) {
        printf("%d\n", ans[i]);
    }

    return 0;
}