RT

#include<iostream>
#include<cstring>
#include<cstdio>
#include<algorithm>
#include<cmath>
#include<ctime>
#include<queue>
#include<string>
#include<bitset>
#include<cctype>
#include<cstdlib>
#include<functional>
#include<istream>
#include<sstream>
#include<streambuf>
#define ll long long 
using namespace std;
const int N=600,inf=0x3f3f3f;
int e[N][N],a[N];
int main()
{
	memset(e,inf,sizeof(e));
	int n,m,cnt,x;
	string s,s1;
    scanf("%d%d",&m,&n);
    for(int i=1;i<=m;i++)
    {
		cnt=0;
		getline(cin,s1);
		getline(cin,s);
		for(int j=0;j<s.length();j++)
		{
			x=0;
			while(s[j]>='0'&&s[j]<='9')
			{
				x=x*10+s[j]-'0';
				i++;
			}
			a[++cnt]=x;
		}
		for(int j=1;j<=cnt;j++)
		{
			e[i][i]=0;
			for(int k=j+1;k<=cnt;k++)
				e[a[j]][a[k]]=1;
		}
	}
	for(int k=1;k<=n;k++)
		for(int i=1;i<=n;i++)
			for(int j=1;j<=n;j++)
				if(i!=j&&i!=k&&j!=k)
					e[i][j]=min(e[i][j],e[i][k]+e[k][j]);
	if(e[1][n]==inf)
		printf("NO");
	else
		printf("%d",e[1][n]);
    return 0;
}