/*Source Code
Problem: 1003
Username: 2010201211
Run Time: 736MS
Memory: 1084K
Language:C++
JudgeStatus: Accepted*/
#include <iostream>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
using namespace std;
#define E 60000
#define V 700
#define inf 0x3F3F3F3F
struct Edge
{int u,v,c,next;
}edge[E*2];
int cnt;
int dist[V];
int head[V];
int que[V];
int sta[V];void init(){cnt=0;memset(head,-1,sizeof(head));
}
void addedge(int u,int v,int c){edge[cnt].u=u;edge[cnt].v=v;edge[cnt].c=c;edge[cnt].next=head[u];head[u]=cnt++;edge[cnt].u=v;edge[cnt].v=u;edge[cnt].c=0;edge[cnt].next=head[v];head[v]=cnt++;
}int dinic(int s,int t){int ans=0;while(true){int left,right,u,v;memset(dist,-1,sizeof(dist));left=right=0;que[right++]=s;dist[s]=0;while(left<right){//bfs构造层次网络u=que[left++];for(int k=head[u];k!=-1;k=edge[k].next){u=edge[k].u;v=edge[k].v;if(edge[k].c>0 && dist[v]==-1){dist[v]=dist[u]+1;que[right++]=v;if(v==t){left=right;break;}}}}if(dist[t]==-1) break;//汇点不在层次网络中,算法结束.int top=0;int now=s;while(true){//层次图中进行一次dfs增广if(now!=t){//dfs未到汇点int k;for(k=head[now];k!=-1;k=edge[k].next){//判断now之后是否有可用点(入度是否为0)if(edge[k].c>0 && dist[edge[k].u]+1==dist[edge[k].v]) break;}if(k!=-1){//如果now之后有可用点(入度>0)//cout << top << endl;sta[top++]=k;//边入栈now=edge[k].v;}else{//now之后没有可用点if(top==0) break;dist[edge[sta[--top]].v]=-1;//从p和层次图中删除点u以及u连接的所有边
now=edge[sta[top]].u;}}else{//dfs到汇点int flow=inf,ebreak;//(1)增广pfor(int i=0;i<top;i++){if(flow>edge[sta[i]].c){flow=edge[sta[i]].c;ebreak=i;}}ans+=flow;for(int i=0;i<top;i++){edge[sta[i]].c-=flow;//正向边减流edge[sta[i]^1].c+=flow;//反向边加流
                }//(2)退至p中从源点可到达的最后一个顶点now=edge[sta[ebreak]].u;top=ebreak;}}}return ans;
}int main()
{//freopen("in.txt","r",stdin);int n,m,k,cptor[105],a,map[505][105];while(scanf("%d%d",&n,&m)!=EOF){memset(cptor,0,sizeof(cptor));memset(map,0,sizeof(map));for(int i=1;i<=n;i++){scanf("%d",&k);for(int j=1;j<=k;j++){scanf("%d",&a);map[i][a]=1;cptor[a]++;}}int maxc=-1;for(int i=1;i<=m;i++){maxc=max(maxc,cptor[i]);}int mid,log=0;int left=0,right=maxc+1;while(left<right){mid=(left+right)/2;init();for(int i=1;i<=m;i++){if(cptor[i]>mid) addedge(0,i,mid);else addedge(0,i,cptor[i]);for(int j=1;j<=n;j++){if(map[j][i]==1){addedge(i,m+j,1);}}}for(int i=1;i<=n;i++){addedge(m+i,m+n+1,1);}int res=dinic(0,m+n+1);if(res==n) {right=mid;log=mid;}else left=mid+1;}printf("%d\n",log);}return 0;
}