Funny Gnomes

#include<bits/stdc++.h>
using namespace std;

const int M = 500;
const int B = 30;

int n, m;

class matrix
{
public:

    bitset<M> r[M], c[M];
    int dim;

    matrix()
    {

    }

    matrix(int _dim)
    {
        dim = _dim;
    }

    void reset()
    {
        for (int i = 0; i < dim; i++)
        {
            r[i].reset();
            c[i].reset();
        }
    }

    void makeiden()
    {
        reset();
        for (int i = 0; i < dim; i++)
        {
            r[i][i] = 1;
            c[i][i] = 1;
        }
    }

    matrix operator * (const matrix &m) const
    {
        matrix res(dim);
        for (int i = 0; i < dim; i++)
        {
            for (int j = 0; j < dim; j++)
            {
                res.r[i][j] = ((r[i] & m.c[j]).count() > 0);
                res.c[j][i] = res.r[i][j];
            }
        }
        return res;
    }
};

matrix obj[B];

matrix power(matrix a, int b)
{
    matrix res(a.dim);
    res.makeiden();
    while (b > 0)
    {
        if (b & 1)
        {
            res = res * a;
        }
        a = a * a;
        b >>= 1;
    }
    return res;
}

void prepare()
{
    for (int i = 1; i < B; i++)
    {
        obj[i] = obj[i - 1] * obj[i - 1];
    }
}

bitset<M> fast_power(int x, int k)
{
    bitset<M> res;
    res[x] = 1;
    for (int pos = B - 1; pos >= 0; pos--)
    {
        if (k & (1LL << pos))
        {
            bitset<M> prev = res;
            for (int i = 0; i < n; i++)
            {
                res[i] = ((prev & obj[pos].c[i]).count() > 0);
            }
        }
    }
    return res;
}

signed main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL); cout.tie(NULL);

#ifndef ONLINE_JUDGE
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
#endif

    cin >> n;
    for (int i = 0; i < B; i++)
    {
        obj[i] = matrix (n);
    }
    for (int i = 0; i < n; i++)
    {
        for (int j = 0; j < n; j++)
        {
            int x;
            cin >> x;
            obj[0].r[i][j] = obj[0].c[j][i] = x;
        }
    }
    prepare();
    cin >> m;
    for (int i = 0; i < m; i++)
    {
        int k, x;
        cin >> k >> x;
        --x;
        bitset<M> res = fast_power(x, k);
        vector<int> ans;
        for (int j = 0; j < n; j++)
        {
            if (res[j])
            {
                ans.push_back(j + 1);
            }
        }
        cout << ans.size() << endl;
        if (ans.size() == 0)
        {
            cout << -1 << '\n';
        }
        else
        {
            for (auto &v : ans)
            {
                cout << v << " ";
            }
            cout << '\n';
        }
    }
    return 0;
}