#include<iostream>
#include<fstream>
#include<cstdio>
#include<cmath>
#include<cstdlib>
#define member_max 1001
#define team_max 101
struct team
{
	bool flag;
	int member[member_max];
	int pos;
	bool fla[member_max];
};
struct person
{
	int serve;
	bool fla;
	int teamin[team_max];
	int pos;
};
int n,m;
team data[team_max];
person dat[member_max];
using namespace std;
int main()
{
	int i,j,a,b;
	int sor[member_max][2];

	freopen("cookie.in","r",stdin);
	freopen("cookie.out","w",stdout);
	scanf("%d%d",&n,&m);
	memset(data,0,sizeof(data));
	memset(dat,0,sizeof(dat));
	memset(sor,0,sizeof(sor));
	for (i=1;i<=m;i++)
	{
		scanf("%d",&a);
		for (j=1;j<=a;j++)
		{
			scanf("%d",&b);
			data[i].member[data[i].pos]=b;
			dat[i].teamin[dat[i].pos]=i;
			data[i].pos++;
			dat[i].pos++;
		}
	}
	printf("%d",-1);
	return 0;
}