#include <bits/stdc++.h>
 
#define _overload(_1,_2,_3,name,...) name
#define _rep(i,n) _range(i,0,n)
#define _range(i,a,b) for(int i=(int)(a);i<(int)(b);++i)
#define rep(...) _overload(__VA_ARGS__,_range,_rep,)(__VA_ARGS__)
 
#define _rrep(i,n) _rrange(i,n,0)
#define _rrange(i,a,b) for(int i=(int)(a)-1;i>=(int)(b);--i)
#define rrep(...) _overload(__VA_ARGS__,_rrange,_rrep,)(__VA_ARGS__)
 
#define _all(arg) begin(arg),end(arg)
#define uniq(arg) sort(_all(arg)),(arg).erase(unique(_all(arg)),end(arg))
#define getidx(ary,key) lower_bound(_all(ary),key)-begin(ary)
#define clr(a,b) memset((a),(b),sizeof(a))
#define bit(n) (1LL<<(n))
 
// #define DEBUG
 
#ifdef DEBUG
    #define dump(...) fprintf(stderr, __VA_ARGS__)
#else
    #define dump(...)
#endif
 
template<class T>bool chmax(T &a, const T &b) { return (a<b)?(a=b,1):0;}
template<class T>bool chmin(T &a, const T &b) { return (b<a)?(a=b,1):0;}
 
using namespace std;
using ll=long long;
using vi=vector<int>;
using vll=vector<ll>;
 
const double EPS = 1e-10;
const double PI = acos(-1.0);
const ll inf =1LL << 62;
const ll mod=1000000007LL;
const int dx[4]={1,0,-1,0};
const int dy[4]={0,1,0,-1};
 
 
ll extgcd(ll a,ll b,ll& x,ll& y){x=1,y=0;ll g=a;if(b!=0) g=extgcd(b,a%b,y,x),y-=a/b*x;return g;}
ll ADD(const ll &a, const ll &b,const ll &mod) { return (a+b)%mod;}
ll SUB(const ll &a, const ll &b,const ll &mod) { return (a-b+mod)%mod;}
ll MUL(const ll &a, const ll &b,const ll &mod) { return (1LL*a*b)%mod;}
ll DIV(const ll &a, const ll &b,const ll &mod) {ll x,y; extgcd(b,mod,x,y);return MUL(a,(x+mod)%mod,mod);}
 
random_device rd;
mt19937 mt(rd());
uniform_int_distribution<int> dice(1,6);
uniform_real_distribution<double> score(0.0,10.0);

using R = long double;

int main(void){
    cin.tie(0);
    ios::sync_with_stdio(false);

    for(int n; cin >> n, n;){
        vector<R> p(n);
        vector<vi> a(n);
        vector<vi> adj(n, vi(n));
        rep(i, n){
            cin >> p[i];
            int m; cin >> m;
            a[i] = vi(m); for(auto& e : a[i]) cin >> e, e--, adj[i][e] = true;
        }

        vector<vi> cango(n, vi(n));
        rep(i, n){
            cango[i][i] = true;
            for(auto& j : a[i]){
                cango[i][j] = true;
            }
        }
        rep(k, n) rep(i, n) rep(j, n) cango[i][j] |= (cango[i][k] & cango[k][j]);

        int m = 0;
        vi group(n, -1);
        rep(i, n){
            if(group[i] != -1) continue;
            rep(j, i, n){
                if(cango[i][j] & cango[j][i]){
                    assert(group[j] == -1);
                    group[j] = m;
                }
            }
            m++;
        }

        vector<set<int>> edge(m);
        rep(i, n){
            rep(j, n){
                if(group[i] == group[j]) continue;
                if(adj[i][j]){
                    edge[group[j]].insert(group[i]);
                }
            }
        }

        vector<R> q(m, 1.0);
        rep(i, n){
            q[group[i]] *= p[i];
        }

        R res = 1.0;
        rep(i, m){
            if(edge[i].size() >= 1) continue;
            res *= ((R)1.0 - q[i]);
        }

        cout.precision(10);
        cout << fixed << res << endl;
    }

    return 0;
}

Measured memory_bytes: 3384