constexpr ll mod = 1'000'000'007; vector BerlekampMassey(const vector& s) { int n = sz(s), L = 0, m = 0; vector C(n), B(n), T; C[0] = B[0] = 1; ll b = 1; for (int i = 0; i < n; i++) { m++; ll d = s[i] % mod; for (int j = 1; j <= L; j++) { d = (d + C[j] * s[i - j]) % mod; } if (!d) continue; T = C; ll coef = d * powMod(b, mod-2, mod) % mod; for (int j = m; j < n; j++) { C[j] = (C[j] - coef * B[j - m]) % mod; } if (2 * L > i) continue; L = i + 1 - L; swap(B, T); b = d; m = 0; } C.resize(L + 1); C.erase(C.begin()); for (auto& x : C) x = (mod - x) % mod; return C; }