// naive #include #include #include #include #include #include int sgn(int x) { return x == 0 ? 0 : x > 0 ? +1 : -1; } bool intersect(int x1, int y1, int x2, int y2, int x3, int y3, int x4, int y4) { int d3 = (x2 - x1) * (y3 - y1) - (y2 - y1) * (x3 - x1); int d4 = (x2 - x1) * (y4 - y1) - (y2 - y1) * (x4 - x1); int d1 = (x4 - x3) * (y1 - y3) - (y4 - y3) * (x1 - x3); int d2 = (x4 - x3) * (y2 - y3) - (y4 - y3) * (x2 - x3); return sgn(d1) * sgn(d2) < 0 and sgn(d3) * sgn(d4) < 0; } int main() { int n, m; std::cin >> n >> m; using mint = atcoder::modint; mint::set_mod(m); std::vector> points; for (int x = 1; x <= 2 * n; ++x) { for (int y = 1; x + y <= 2 * n; ++y) { if ((x + y) % 2 == 0) points.emplace_back(x, y); } } const int k = points.size(); assert(k == n * n); if (n <= 3) { std::vector> edges; for (int i = 0; i < k; ++i) for (int j = i + 1; j < k; ++j) { auto [xi, yi] = points[i]; auto [xj, yj] = points[j]; if (::abs(xi - xj) + ::abs(yi - yj) == 2) { edges.emplace_back(i, j); } } const int l = edges.size(); std::vector ng_subset; for (int i = 0; i < l; ++i) for (int j = i + 1; j < l; ++j) { auto [a, b] = edges[i]; auto [c, d] = edges[j]; auto [xa, ya] = points[a]; auto [xb, yb] = points[b]; auto [xc, yc] = points[c]; auto [xd, yd] = points[d]; if (intersect(xa, ya, xb, yb, xc, yc, xd, yd)) { ng_subset.push_back((1 << i) | (1 << j)); } } mint ans = 0; for (int s = 0; s < 1 << l; ++s) { if (__builtin_popcount(s) != k - 1) { continue; } bool ok = true; for (int ng : ng_subset) { if ((ng & s) == ng) { ok = false; break; } } if (not ok) { continue; } std::vector> g(k); for (int i = 0; i < l; ++i) if ((s >> i) & 1) { auto [u, v] = edges[i]; g[u].push_back(v); g[v].push_back(u); } int cnt = 0; std::vector dist(k, -1); dist[0] = 0; std::deque dq{ 0 }; while (dq.size()) { int u = dq.front(); dq.pop_front(); auto [x, y] = points[u]; ++cnt; if (dist[u] != (x + y) / 2 - 1) { ok = false; break; } for (int v : g[u]) if (dist[v] == -1) { dist[v] = dist[u] + 1; dq.push_back(v); } } ok &= cnt == k; if (not ok) { continue; } mint w = 1; for (int i = 0; i < k; ++i) if (g[i].size() == 1) { w *= points[i].first; } ans += w; } std::cout << ans.val() << std::endl; } else if (n == 4) { std::vector> edges; for (int i = 0; i < k; ++i) for (int j = i + 1; j < k; ++j) { auto [xi, yi] = points[i]; auto [xj, yj] = points[j]; if (::abs(xi - xj) + ::abs(yi - yj) == 2 and xi + yi != xj + yj) { edges.emplace_back(i, j); } } const int l = edges.size(); std::vector ng_subset; for (int i = 0; i < l; ++i) for (int j = i + 1; j < l; ++j) { auto [a, b] = edges[i]; auto [c, d] = edges[j]; auto [xa, ya] = points[a]; auto [xb, yb] = points[b]; auto [xc, yc] = points[c]; auto [xd, yd] = points[d]; if (intersect(xa, ya, xb, yb, xc, yc, xd, yd)) { ng_subset.push_back((1 << i) | (1 << j)); } } mint ans = 0; for (int s = 0; s < 1 << l; ++s) { if (__builtin_popcount(s) != k - 1) { continue; } bool ok = true; for (int ng : ng_subset) { if ((ng & s) == ng) { ok = false; break; } } if (not ok) { continue; } std::vector> g(k); for (int i = 0; i < l; ++i) if ((s >> i) & 1) { auto [u, v] = edges[i]; g[u].push_back(v); g[v].push_back(u); } int cnt = 0; std::vector dist(k, -1); dist[0] = 0; std::deque dq{ 0 }; while (dq.size()) { int u = dq.front(); dq.pop_front(); auto [x, y] = points[u]; ++cnt; if (dist[u] != (x + y) / 2 - 1) { ok = false; break; } for (int v : g[u]) if (dist[v] == -1) { dist[v] = dist[u] + 1; dq.push_back(v); } } ok &= cnt == k; if (not ok) { continue; } mint w = 1; for (int i = 0; i < k; ++i) if (g[i].size() == 1) { w *= points[i].first; } ans += w; } std::cout << ans.val() << std::endl; } else if (n <= 9) { mint ans = 1; for (int t = 1; t < n; ++t) { mint sumw = 0; const int l = 4 * (t - 1); for (int s = 0; s < 1 << l; ++s) { if (s & (s >> 1)) continue; std::vector c(2 * t - 1); for (int i = 1; i <= 2 * t - 3; ++i) { c[i] += (s >> (2 * i - 2)) & 1; c[i] += (s >> (2 * i + 1)) & 1; c[i] += ((s >> (2 * i - 1)) & 1) == 0 and ((s >> (2 * i)) & 1) == 0; } mint w = 1; for (int i = 1; i <= 2 * t - 3; ++i) { if (c[i] == 0) { w *= i + 1; } } sumw += w; } ans *= sumw; } for (int i = 1; i <= 2 * n - 1; ++i) { ans *= i; } std::cout << ans.val() << std::endl; } else { while(1); } }