#include using namespace std; using lint = long long int; using pint = pair; using plint = pair; struct fast_ios { fast_ios(){ cin.tie(0); ios::sync_with_stdio(false); cout << fixed << setprecision(20); }; } fast_ios_; #define ALL(x) (x).begin(), (x).end() #define SZ(x) ((lint)(x).size()) #define POW2(n) (1LL << (n)) #define FOR(i, begin, end) for(int i=(begin),i##_end_=(end);i=i##_begin_;i--) #define REP(i, n) FOR(i,0,n) #define IREP(i, n) IFOR(i,0,n) template void ndarray(vector &vec, int len) { vec.resize(len); } template void ndarray(vector &vec, int len, Args... args) { vec.resize(len); for (auto &v : vec) ndarray(v, args...); } template bool mmax(T &m, const T q) { if (m < q) {m = q; return true;} else return false; } template bool mmin(T &m, const T q) { if (m > q) {m = q; return true;} else return false; } template pair operator+(const pair &l, const pair &r) { return make_pair(l.first + r.first, l.second + r.second); } template pair operator-(const pair &l, const pair &r) { return make_pair(l.first - r.first, l.second - r.second); } template istream &operator>>(istream &is, vector &vec){ for (auto &v : vec) is >> v; return is; } ///// This part below is only for debug, not used ///// template ostream &operator<<(ostream &os, const vector &vec){ os << "["; for (auto v : vec) os << v << ","; os << "]"; return os; } template ostream &operator<<(ostream &os, const deque &vec){ os << "deq["; for (auto v : vec) os << v << ","; os << "]"; return os; } template ostream &operator<<(ostream &os, const set &vec){ os << "{"; for (auto v : vec) os << v << ","; os << "}"; return os; } template ostream &operator<<(ostream &os, const unordered_set &vec){ os << "{"; for (auto v : vec) os << v << ","; os << "}"; return os; } template ostream &operator<<(ostream &os, const multiset &vec){ os << "{"; for (auto v : vec) os << v << ","; os << "}"; return os; } template ostream &operator<<(ostream &os, const unordered_multiset &vec){ os << "{"; for (auto v : vec) os << v << ","; os << "}"; return os; } template ostream &operator<<(ostream &os, const pair &pa){ os << "(" << pa.first << "," << pa.second << ")"; return os; } template ostream &operator<<(ostream &os, const map &mp){ os << "{"; for (auto v : mp) os << v.first << "=>" << v.second << ","; os << "}"; return os; } template ostream &operator<<(ostream &os, const unordered_map &mp){ os << "{"; for (auto v : mp) os << v.first << "=>" << v.second << ","; os << "}"; return os; } #define dbg(x) cerr << #x << " = " << (x) << " (L" << __LINE__ << ") " << __FILE__ << endl; ///// END ///// /* #include #include #include using namespace __gnu_pbds; // find_by_order(), order_of_key() template using pbds_set = tree, rb_tree_tag, tree_order_statistics_node_update>; template using pbds_map = tree, rb_tree_tag, tree_order_statistics_node_update>; */ vector A; long double logval(int i, int j) { return log(A[i] + A[j]) + A[j] * log(A[i]); } lint power(lint x, lint n, lint MOD) { lint ans = 1; while (n>0) { if (n & 1) (ans *= x) %= MOD; (x *= x) %= MOD; n >>= 1; } return ans; } using cmplx = complex; void fft(int N, vector &a, double dir) { int i = 0; FOR(j, 1, N - 1) { for (int k = N >> 1; k > (i ^= k); k >>= 1); if (j < i) swap(a[i], a[j]); } vector zeta_pow(N); REP(i, N) { double theta = M_PI / N * i * dir; zeta_pow[i] = cmplx(cos(theta), sin(theta)); } for (int m = 1; m < N; m *= 2) REP(y, m) { cmplx fac = zeta_pow[N / m * y]; for (int x = 0; x < N; x += 2 * m) { int u = x + y; int v = x + y + m; cmplx s = a[u] + fac * a[v]; cmplx t = a[u] - fac * a[v]; a[u] = s; a[v] = t; } } } template vector conv_cmplx(const vector &a, const vector &b) { int N = 1; while (N < (int)a.size() + (int)b.size()) N *= 2; vector a_(N), b_(N); REP(i, a.size()) a_[i] = a[i]; REP(i, b.size()) b_[i] = b[i]; fft(N, a_, 1); fft(N, b_, 1); REP(i, N) a_[i] *= b_[i]; fft(N, a_, -1); REP(i, N) a_[i] /= N; return a_; } vector conv_lint(const vector &a, const vector &b) { vector ans = conv_cmplx(a, b); vector ret(ans.size()); REP(i, ans.size()) ret[i] = floor(ans[i].real() + 0.5); return ret; } lint extgcd(lint a, lint b, lint &x, lint &y) { lint d = a; if (b != 0) d = extgcd(b, a % b, y, x), y -= (a / b) * x; else x = 1, y = 0; return d; } // Calc a^(-1) (MOD m) lint mod_inverse(lint a, lint m) { lint x, y; extgcd(a, m, x, y); return (m + x % m) % m; } // mod: 素数, primitive_root: modの原始根 is_inverse: trueならば逆変換 void fft_mod(vector &a, lint mod, lint primitive_root, bool is_inverse=false) { int n = a.size(); lint h = power(primitive_root, (mod - 1) / n, mod); if (is_inverse) h = mod_inverse(h, mod); int i = 0; FOR(j, 1, n - 1) { for (int k = n >> 1; k > (i ^= k); k >>= 1); if (j < i) swap(a[i], a[j]); } for (int m = 1; m < n; m *= 2) { int m2 = 2 * m; lint base = power(h, n / m2, mod); lint w = 1; REP(x, m) { for (int s = x; s < n; s += m2) { lint u = a[s], d = a[s + m] * w % mod; a[s] = u + d - (u + d >= mod ? mod : 0), a[s + m] = u - d + (u - d < 0 ? mod : 0); } w = w * base % mod; } } for (auto &v : a) v = (v < 0 ? v + mod : v); if (is_inverse) { lint n_inv = mod_inverse(n, mod); for (auto &v : a) v = v * n_inv % mod; } } // MOD modにおける畳み込み演算 retval[i] = \sum_j a[j] b[i - j] vector convolution_mod(vector a, vector b, lint mod, lint primitive_root) { int sz = 1; while (sz < a.size() + b.size()) sz <<= 1; a.resize(sz), b.resize(sz); fft_mod(a, mod, primitive_root, false), fft_mod(b, mod, primitive_root, false); REP(i, sz) a[i] = a[i] * b[i] % mod; fft_mod(a, mod, primitive_root, true); return a; } plint linear_congruence(const vector &A, const vector &B, const vector &M) { lint x = 0, m = 1; REP(i, A.size()) { lint a = A[i] * m, b = B[i] - A[i] * x, d = __gcd(M[i], a); if (b % d != 0) return plint(0, -1); // 解なし lint t = b / d * mod_inverse(a / d, M[i] / d) % (M[i] / d); x += m * t; m *= M[i] / d; } return plint((x < 0 ? x + m : x), m); } constexpr lint MOD = 1000000007; int main() { int N; cin >> N; A.resize(N); cin >> A; int m1 = 0, m2 = 1, mini = 0; vector cou(100001); for (auto v : A) cou[v]++; FOR(i, 1, N) { if (logval(mini, i) < logval(m1, m2)) m1 = mini, m2 = i; if (A[i] < A[mini]) mini = i; } auto vconv = convolution_mod(cou, cou, 1224736769, 3); auto vconv2 = convolution_mod(cou, cou, 469762049, 3); FOR(d, 1, vconv.size()) { auto p = linear_congruence(vector{1, 1}, vector{vconv[d], vconv2[d]}, vector{1224736769, 469762049}); vconv[d] = p.first; } lint den = (A[m1] + A[m2]) % MOD * power(A[m1], A[m2], MOD) % MOD; lint num = 1; vector AA(N + 1); REP(i, N) AA[i + 1] = A[i] + AA[i]; REP(i, N) num = num * power(A[i], AA[N] - AA[i + 1], MOD) % MOD; FOR(d, 1, vconv.size()) if (vconv[d]) { if (d % 2) { num = num * power(d, vconv[d] / 2, MOD) % MOD; } else { lint n = (vconv[d] - cou[d / 2] * cou[d / 2]) / 2 + cou[d / 2] * (cou[d / 2] - 1) / 2; num = num * power(d, n, MOD) % MOD; } } cout << num * power(den, MOD - 2, MOD) % MOD << endl; }