#include <iostream>
#include <iomanip>
#include <cstdio>
#include <string>
#include <cstring>
#include <deque>
#include <list>
#include <queue>
#include <stack>
#include <vector>
#include <utility>
#include <algorithm>
#include <map>
#include <set>
#include <complex>
#include <cmath>
#include <limits>
#include <cfloat>
#include <climits>
#include <ctime>
#include <cassert>
#include <numeric>
#include <functional>
using namespace std;

#define rep(i,a,n) for(int (i)=(a); (i)<(n); (i)++)
#define repq(i,a,n) for(int (i)=(a); (i)<=(n); (i)++)
#define repr(i,a,n) for(int (i)=(a); (i)>=(n); (i)--)
#define int long long int

template<typename T> void chmax(T &a, T b) {a = max(a, b);}
template<typename T> void chmin(T &a, T b) {a = min(a, b);}
template<typename T> void chadd(T &a, T b) {a = a + b;}

typedef pair<int, int> pii;
typedef long long ll;

int dx[] = {0, 0, 1, -1};
int dy[] = {1, -1, 0, 0};
constexpr ll INF = 1001001001001001LL;
constexpr ll MOD = 1000000007LL;

// ?§?????????¨????????¨???????????????????¨???????????§???????
template <typename T>
struct Edge {
    int from, to;
    T cost;
    Edge(int s, T d) : to(s), cost(d) {}
    Edge(int f, int s, T d) : from(f), to(s), cost(d) {}

    bool operator<(const Edge &e) const {
        return cost < e.cost;
    }
    bool operator>(const Edge &e) const {
        return cost > e.cost;
    }
};

template <typename T>
using Graph = vector< vector< Edge<T> > >;

template <typename T>
struct GraphSCC {
public:
    const int n;
    vector<bool> isthrough;
    vector<int> vs, cmp;
    vector< vector< Edge<T> > > G, rG;
    vector< vector<int> > H;

    GraphSCC(vector< vector< Edge<T> > > &_G) :
        n(_G.size()), isthrough(n, false), cmp(n, 0), G(_G), rG(n) {
            // ????????°??????
            for(int i=0; i<n; i++) for(int j=0; j<G[i].size(); j++)
                rG[ G[i][j].to ].push_back(Edge<T>(i, G[i][j].cost));
        }

    void SCC_dfsone(int cur) {
        isthrough[cur] = true;
        for(int i=0; i<G[cur].size(); i++) {
            if(!isthrough[G[cur][i].to]) {
                SCC_dfsone(G[cur][i].to);
            }
        }
        vs.push_back(cur);
    }

    void SCC_dfstwo(vector<int> &vec, int cur, int k) {
        cmp[cur] = k;
        isthrough[cur] = true;
        vec.push_back(cur);
        for(int i=0; i<rG[cur].size(); i++) {
            if(!isthrough[rG[cur][i].to]) {
                SCC_dfstwo(vec, rG[cur][i].to, k);
            }
        }
    }

    pair<vector<int>, int> scc() {
        // 1?????????DFS
        for(int i=0; i<n; i++)
            if(!isthrough[i]) SCC_dfsone(i);

        fill(isthrough.begin(), isthrough.end(), false);
        reverse(vs.begin(), vs.end());
        int k = 0; vector< vector<int> > S;

        // 2?????????DFS
        for(int i=0; i<vs.size(); i++) {
            if(!isthrough[vs[i]]) {
                S.push_back(vector<int>());
                SCC_dfstwo(S.back(), vs[i], k++);
            }
        }

        H.resize(k);
        fill(isthrough.begin(), isthrough.end(), false);
        for(int i=0; i<k; i++) {
            for(int j=0; j<S[i].size(); j++) {
                int v = S[i][j];
                for(int x=0; x<G[v].size(); x++) {
                    int u = G[v][x].to;
                    if(isthrough[cmp[u]] || cmp[v] == cmp[u]) continue;
                    isthrough[cmp[u]] = true;
                    H[cmp[v]].push_back(cmp[u]);
                }
            }
            for(int j=0; j<H[i].size(); j++) isthrough[ H[i][j] ] = false;
        }
        return make_pair(cmp, k);
    }
};

int N, M, deg[110];
double p[110];

signed main() {
    while(cin >> N, N) {
        memset(deg, 0, sizeof(deg));
        Graph<int> G(N);
        rep(i,0,N) {
            cin >> p[i] >> M;
            rep(j,0,M) {
                int v; cin >> v; v--;
                G[i].push_back(Edge<int>(v, 1));
            }
        }

        GraphSCC<int> gs(G);
        // SCC ??????????????????????±?????????????SCC ??????????????°
        pair< vector<int>, int > res = gs.scc();

        // ??\?¬???°????¨????
        rep(i,0,res.second) for(auto x : gs.H[i]) deg[x]++;
        double ans = 1.0;
        rep(i,0,res.second) {
            // ??\?¬???° 0 ??????????????????????¨????
            if(deg[i]) continue;
            // printf("zero degree: node %lld\n", i);
            double temp = 1.0;
            rep(j,0,N) {
                // ????????£?????????????±?????????´???????????????
                if(res.first[j] == i) {
                    // printf("same: %lld\n", j+1);
                    temp *= p[j];
                }
            }
            ans *= (1 - temp);
        }
        printf("%.12f\n", ans);
    }
    return 0;
}

Measured memory_bytes: 3884