#include <algorithm>
#include <bitset>
#include <complex>
#include <deque>
#include <exception>
#include <fstream>
#include <functional>
#include <iomanip>
#include <ios>
#include <iosfwd>
#include <iostream>
#include <istream>
#include <iterator>
#include <limits>
#include <list>
#include <locale>
#include <map>
#include <memory>
#include <new>
#include <numeric>
#include <ostream>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <stdexcept>
#include <streambuf>
#include <string>
#include <typeinfo>
#include <utility>
#include <valarray>
#include <vector>
#include <climits>
#include <cstring>
#include <cassert>


using namespace std;
#define SZ(x) (int)(x.size())
#define REP(i, n) for(int i=0;i<n;++i)
#define FOR(i, a, b) for(int i=a;i<b;++i)
#define RREP(i, n) for(int i=n-1;i>=0;--i)
#define RFOR(i, a, b) for(int i=b-1;i>=a;--i)

#define all(x) begin(x),end(x)
#define dump(x) cerr<<#x<<" = "<<(x)<<endl
#define debug(x) cerr<<#x<<" = "<<(x)<<" (L"<<__LINE__<<")"<< endl;

using ll = long long;
using vi = vector<int>;
using vvi = vector<vi>;
using vll = vector<ll>;
using vvll = vector<vll>;
using P = pair<int, int>;
const double eps = 1e-8;
const ll MOD = 1000000007;
const int INF = INT_MAX / 2;
const ll LINF = LLONG_MAX / 2;

template<class T>
bool chmax(T &a, const T &b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}

template<class T>
bool chmin(T &a, const T &b) {
    if (b < a) {
        a = b;
        return true;
    }
    return false;
}


template<typename T1, typename T2>
ostream &operator<<(ostream &os, const pair<T1, T2> p) {
    os << p.first << ":" << p.second;
    return os;
}

template<class T>
ostream &operator<<(ostream &os, const vector<T> &v) {
    os << "[";
    REP(i, SZ(v)) {
        if (i) os << ", ";
        os << v[i];
    }
    return os << "]";
}

// edit

struct Solve {

    int N;
    vector<vector<int>> G;
    vector<vector<int>> rG;
    vector<double> p;
    vector<bool> check;

    double dfs(int n) {
        if (check[n]) {
            return 1;
        }
        check[n] = true;

        double ret = 1.;
        ret *= p[n];
        for (auto e : G[n]) {
            ret *= dfs(e);
        }

        return ret;
    }

    bool solve() {
        cin >> N;
        if (N == 0) return false;
        G.resize(N, vector<int>());
        rG.resize(N, vector<int>());
        p.resize(N, 0.0);
        check.resize(N, false);

        REP(i, N) {
            int n;
            cin >> p[i];
            cin >> n;
            REP(j, n) {
                int c;
                cin >> c;
                c--;
                G[i].push_back(c);
                rG[c].push_back(i);
            }
        }

        double ans = 1.;

        REP(i, N) {
            if (SZ(rG[i]) == 0) {
                ans *= 1. - p[i];
                dfs(i);
            }
        }

        REP(i, N) {
            if (!check[i]) {
                double tapu = dfs(i);
                ans *= 1. - tapu;
            }
        }

        cout << ans << endl;

        return true;

    }

};

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(10);
//    std::ifstream in("input.txt");
//    std::cin.rdbuf(in.rdbuf());

    while (Solve().solve());


    return 0;
}



Measured memory_bytes: 3436