#include <bits/stdc++.h>

#define REP(i, n) for(int i = 0 ; i< (int)n; ++i)

using namespace std;



bool testcase(){
	int n;

	if(!(cin >> n))return false;
	int k;
	cin >> k;
	
	std::vector<int> counts(k);

	vector<vector<int>> stands(n);
	for(int i = 0; i < n; i++)
	{
		int l;
		cin >> l;
		for(int j = 0; j < l; j++)
		{
			int s;
			cin >> s;
			s--;
			stands[i].push_back(s);
		}
	}

	int nempty = k;
	int ntotal = 0;

	int start = 0;
	int end = 0;

	int best = 1000000000;

	for(auto& z : stands[start])
	{
		if(counts[z] == 0)
			nempty--;
		counts[z] += 1;
		ntotal += 1;
	}

	while(true)
	{
		while(nempty > 0)
		{
			end = (end + 1) % n;
			if(end == start)
			{
				if(best == 1000000000)
					cout << -1 << endl;
				else
					cout << best << endl;
				return true;
			}
			for(auto& z : stands[end])
			{
				if(counts[z] == 0)
					nempty--;
				counts[z] += 1;
				ntotal += 1;
			}
		}
		//cerr << start << " " << end << " " << ntotal << endl;
		if(ntotal < best)
			best = ntotal;
		
		for(auto& z : stands[start])
		{
			if(counts[z] == 1)
				nempty++;
			counts[z] -= 1;
			ntotal -= 1;
		}
		if(start == end)
		{
			end = (end + 1) % n;
			for(auto& z : stands[end])
			{
				if(counts[z] == 0)
					nempty--;
				counts[z] += 1;
				ntotal += 1;
			}
		}
		start = (start + 1) % n;
		if(start == 0)
			break;
	}
	if(best == 1000000000)
		cout << -1 << endl;
	else
		cout << best << endl;
	return true;
}


int main(){
	while(testcase());
	return 0;
}