// clang-format off
#include <bits/stdc++.h>
#define int long long
#define main signed main()
#define loop(i, a, n) for (int i = (a); i < (n); i++)
#define rep(i, n) loop(i, 0, n)
#define forever for (;;)
#define all(v) (v).begin(), (v).end()
#define rall(v) (v).rbegin(), (v).rend()
#define prec(n) fixed << setprecision(n)
template<typename A> using V = std::vector<A>;
template<typename A> using F = std::function<A>;
template<typename A, typename B> using P = std::pair<A, B>;
using pii = P<int, int>;
using vi = V<int>;
using vd = V<double>;
using vs = V<std::string>;
using vpii = V<pii>;
using vvi = V<vi>;
using vvpii = V<vpii>;
constexpr int INF = sizeof(int) == sizeof(long long) ? 1000000000000000000LL : 1000000000;
constexpr int MOD = 1000000007;
constexpr double PI = 3.14159265358979;
template<typename A, typename B> bool cmin(A &a, const B &b) { return a > b ? (a = b, true) : false; }
template<typename A, typename B> bool cmax(A &a, const B &b) { return a < b ? (a = b, true) : false; }
constexpr bool odd(const int n) { return n & 1; }
constexpr bool even(const int n) { return ~n & 1; }
template<typename T> std::istream &operator>>(std::istream &is, std::vector<T> &v) { for (T &x : v) is >> x; return is; }
template<typename A, typename B> std::istream &operator>>(std::istream &is, std::pair<A, B> &p) { is >> p.first >> p.second; return is; }
using namespace std;
// clang-format on

using Weight = int;
struct Edge {
  int src, dst;
  Weight weight;
  Edge(const int s = 0, const int d = 0, const Weight w = 0) : src(s), dst(d), weight(w) {}
};

using Edges = std::vector<Edge>;
using Array = std::vector<Weight>;
using Matrix = std::vector<Array>;

class Graph {
  std::vector<Edges> g;
  using iterator = std::vector<Edges>::iterator;
  using const_iterator = std::vector<Edges>::const_iterator;

public:
  Graph(const int size = 0) : g(size) {}
  size_t size() const { return g.size(); }
  const Edges &operator[](const int i) const { return g[i]; }
  void addArc(const int src, const int dst, const Weight w = 1) { g[src].emplace_back(src, dst, w); }
  void addEdge(const int node1, const int node2, const Weight w = 1) {
    addArc(node1, node2, w);
    addArc(node2, node1, w);
  }
  iterator begin() { return g.begin(); }
  const_iterator begin() const { return g.begin(); }
  iterator end() { return g.end(); }
  const_iterator end() const { return g.end(); }
};

class SCC {
public:
  std::vector<int> root;
  Graph g;

  SCC(const Graph &g) : g(g) {
    int n = g.size();
    std::vector<int> ord(n);
    {
      int k = n - 1;
      std::vector<int> visited(n), ordered(n);
      for (int i = 0; i < n; i++) {
        if (visited[i]) continue;
        std::stack<int> stk;
        stk.push(i);
        while (stk.size()) {
          int v = stk.top();
          visited[v] = true;
          bool pushed = false;
          for (auto &e : g[v]) {
            if (!visited[e.dst]) {
              stk.push(e.dst);
              pushed = true;
            }
          }
          if (pushed) continue;
          if (!ordered[v]) {
            ordered[v] = true;
            ord[k--] = v;
          }
          stk.pop();
        }
      }
    }
    Graph rg(n);
    for (auto &es : g) {
      for (auto &e : es) rg.addArc(e.dst, e.src, e.weight);
    }
    root = std::vector<int>(n, -1);
    int k = 0;
    for (int u : ord) {
      if (root[u] >= 0) continue;
      std::stack<int> stk;
      stk.push(u);
      while (stk.size()) {
        int v = stk.top();
        stk.pop();
        root[v] = k;
        for (auto &e : rg[v]) {
          if (root[e.dst] == -1) stk.push(e.dst);
        }
      }
      ++k;
    }
  }

  Graph makeDAG() {
    Graph h(g.size());
    for (auto &es : g) {
      for (auto &e : es) {
        if (root[e.src] == root[e.dst]) continue;
        h.addArc(root[e.src], root[e.dst]);
      }
    }
    return h;
  }
};

main {
  int n;
  while (cin >> n, n) {
    vd p(n);
    Graph g(n);
    rep(i, n) {
      cin >> p[i];
      int m;
      cin >> m;
      rep(j, m) {
        int a;
        cin >> a;
        g.addArc(i, --a);
      }
    }

    SCC scc(g);
    vi in(n);
    for (auto &es : scc.makeDAG()) {
      for (auto &e : es) in[e.dst]++;
    }
    vd d(n, 1.0);
    rep(i, n) d[scc.root[i]] *= p[i];

    double ans = 1.0;
    rep(i, n) if (in[i] == 0 && d[i] != 1.0) ans *= 1.0 - d[i];
    cout << prec(32) << ans << endl;
  }
}

