template void ntt(vector>& y, bool idft) { using mll = MLL; int n = y.size(); vector rev(n); for (int i = 0; i < n; ++i) { rev[i] = rev[i >> 1] >> 1; if (i & 1) { rev[i] |= n >> 1; } } for (int i = 0; i < n; ++i) { if (i < rev[i]) { swap(y[i], y[rev[i]]); } } vector roots = { 0, 1 }; if (roots.size() < n) { int k = lsp(roots.size()); roots.resize(n); for (; (1 << k) < n; ++k) { mll e = qpow(31, 1 << lsp(M - 1) - k - 1); for (int i = 1 << k - 1; i < (1 << k); ++i) { roots[2 * i] = roots[i]; roots[2 * i + 1] = roots[i] * e; } } } for (int h = 2; h <= n; h <<= 1) { for (int j = 0; j < n; j += h) { for (int k = j; k < j + h / 2; ++k) { mll u = y[k], t = roots[k - j + h / 2] * y[k + h / 2]; y[k] = u + t; y[k + h / 2] = u - t; } } } if (idft) { reverse(y.begin() + 1, y.end()); for (int i = 0; i < n; ++i) { y[i] /= n; } } } template vector> multiply(const vector>& a, const vector>& b) { using mll = MLL; vector A(a.begin(), a.end()), B(b.begin(), b.end()); int n = 1; while (n < a.size() + b.size()) n <<= 1; A.resize(n), B.resize(n); ntt(A, false), ntt(B, false); for (int i = 0; i < n; ++i) { A[i] *= B[i]; } ntt(A, true); A.resize(a.size() + b.size() - 1); return A; }