#include <stdio.h>
#include <vector>

using namespace std;

int n, k, best = 1000000000;
vector<int> seq[20000000];
int druh[1000005];

int main(){
	while(scanf("%d %d", &n, &k)>=0){
		int a, b;
		best = 1000000000;
		for(int i = 0; i <= k; i++)
			druh[i] = 0;
		for(int i=0;i<n;i++){
			scanf("%d ", &a);
			for(int j = 0; j < a; j++)
			{
				scanf("%d ", &b);
				b--;
				seq[i].push_back(b);
				seq[i+n].push_back(b);
			}
		}
		int ok = 0, eat = 0;
		int st = 0;
		int end = 0;
		while(end <= n)
		{
			if(ok == k)
			{
				if(eat < best)
					best = eat;
				for(int i = 0; i < seq[end].size(); i++)
				{
					druh[seq[end][i]]--;
					if(druh[seq[end][i]] == 0)
						ok--;
				}
				eat -= seq[end].size();
				end++;
			}
			else
			{
				
				for(int i = 0; i < seq[st].size(); i++)
				{
					if(druh[seq[st][i]] == 0)
						ok++;
					druh[seq[st][i]]++;
				}
				eat += seq[st].size();
				st++;
			}
			if(end == 0 && st > n)
				break;
		}
		if(best > 100000000)
			printf("-1\n");
		else
			printf("%d\n", best);
		for(int i = 0; i < 2*n; i++)
			seq[i].clear();
	}
}