I've submitted the following solution, and it got AC:

#include <cstdio>

int main(void)
{
    int N;
    scanf("%d", &N);
    if (N==1)
    {
        printf("3\n2 0 1\n");
    } else
    {
        printf("0\n");
    }
    return 0;
}


Probably, this is a bug in checker