#include <algorithm>
#include <cmath>
#include <climits>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <fstream>
#include <iostream>
#include <list>
#include <map>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <vector>
#include <cassert>
#include <functional>

using namespace std;

#define LOG(...) printf(__VA_ARGS__)
//#define LOG(...)
#define FOR(i,a,b) for(int i=(int)(a);i<(int)(b);++i)
#define REP(i,n) for(int i=0;i<(int)(n);++i)
#define ALL(a) (a).begin(),(a).end()
#define RALL(a) (a).rbegin(),(a).rend()
#define EXIST(s,e) ((s).find(e)!=(s).end())
#define SORT(c) sort((c).begin(),(c).end())
#define RSORT(c) sort((c).rbegin(),(c).rend())
#define CLR(a) memset((a), 0 ,sizeof(a))

typedef long long ll;
typedef unsigned long long ull;
typedef vector<bool> vb;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<vb> vvb;
typedef vector<vi> vvi;
typedef vector<vll> vvll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

const int dx[] = { -1, 0, 1, 0 }; const int dy[] = { 0, 1, 0, -1 };

struct UnionFind {
	vector<int> v;
	UnionFind(int n) : v(n) { for (int i = 0; i < n; i++) v[i] = i; }
	int  find(int x) { return v[x] == x ? x : v[x] = find(v[x]); }
	void unite(int x, int y) { v[find(x)] = find(y); }
};
struct st {
	double late;
	vector<int> call;
};
vector<st> mem;
map<int, int> mpii;
vb called;
int cnt;

double heiro(int first, int idx) {
	double ret = mem[idx].late;
	called[idx] = false;
	REP(i, mem[idx].call.size()) {
		if (called[mem[idx].call[i]]) {
			ret *= heiro(first, mem[idx].call[i]);
		}
	}
	return ret;
}


int main() {
	int n;
	while (cin >> n, n) {
		mem.clear();
		mem.resize(n);
		mpii.clear();
		called.resize(n, false);
		REP(i, n) {
			int m;
			cin >> mem[i].late >> m;
			mem[i].call.resize(m);
			REP(j, m) {
				cin >> mem[i].call[j];
				mem[i].call[j]--;
				called[mem[i].call[j]] = true;
			}
			mpii[i] = i;
		}
		double ans = 1.0;
		queue<int> Q;
		REP(i, n)
			if (called[i] == false) {
				ans *= (1.0 - mem[i].late);
				REP(j, mem[i].call.size())
					Q.push(mem[i].call[j]);
			}
		while (!Q.empty()) {
			int q = Q.front();Q.pop();
			called[q] = false;
			REP(i, mem[q].call.size())
				if (called[mem[q].call[i]])
					Q.push(mem[q].call[i]);
		}
		bool henka;
		do {
			henka = false;
			REP(i, n) {
				if (!called[i])
					continue;
				bool pass = true;
				REP(j, mem[i].call.size())
					if (called[mem[i].call[j]])
						pass = false;
				if (pass) {
					called[i] = false;
					henka = true;
				}
			}
		} while (henka);
			REP(i, n) {
				if (called[i])
					ans *= 1.0 - heiro(i, i);
			}
			printf("%0.9lf\n", ans);
		}
	}