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#include <iostream>
#include <vector>
#include <string>

using lolo = long long;

lolo nwd(lolo a, lolo b);
lolo nww(lolo a, lolo b);

struct Frac {
	lolo li = 0;
	lolo mi = 1;

	Frac& operator+= (Frac const& fr) {
		lolo mult_this  = nww(mi, fr.mi) / mi;
		lolo mult_other = nww(mi, fr.mi) / fr.mi;

		this->li *= mult_this;
		this->li += (fr.li * mult_other);
		this->mi *= mult_this;

		return *this;
	}

	Frac operator/ (lolo n) {
		int dz = nwd(li, n);
		return {li / dz, mi * n / dz};
	}
};

std::ostream& operator<< (std::ostream& os, Frac const& fr) {
	os << fr.li << "/" << fr.mi;
	return os;
}

lolo nwd(lolo a, lolo b) {
	if (a < b) { std::swap(a, b); }
	while (b != 0) {
		a = a % b;
		std::swap(a, b);
	}
	return a;
}

lolo nww(lolo a, lolo b) {
	return a * b / nwd(a, b);
}

lolo solve(std::vector< std::vector< lolo > >& plats) {
	std::vector< Frac > fracs(plats.size(), Frac{0, 1});
	fracs[0] = Frac{1, 1};

	for (int src = 0; src < plats.size(); ++src) {
		if (plats[src].size() == 0) continue;
		Frac split = fracs[src] / plats[src].size();
		for (auto target : plats[src]) {
			fracs[target] += split;
		}
	}

	lolo wynik = 1;
	for (auto f: fracs) {
		wynik = nww(wynik, f.mi);
	}
	return wynik;
}

int main() {
	int l_plat; std::cin >> l_plat;
	std::vector< std::vector< lolo > > plats(l_plat);

	for (int i = 0; i < l_plat; ++i) {
		int num; std::cin >> num;
		for(int k = 0; k < num; ++k) {
			lolo target; std::cin >> target;
			plats[i].push_back(target - 1);
		}
	}

	std::cout << solve(plats) << "\n";
}