#include<cstring>
#include<cstdio>
#include<vector>
const int maxn = 1e3+10;
using std::vector;
vector<int>mp[maxn];
bool vis[maxn];
int cnt[maxn],maxsize[maxn],ylink[maxn][maxn];
int n,m,mid;

bool dfs(int u){
    int len = mp[u].size();
    for(int j=0;j<len;j++){
        int i = mp[u][j];
        if(!vis[i]){
            vis[i]=true;
            if(cnt[i]<mid){
                ylink[i][++cnt[i]]=u;
                return true;
            }else {
                for(int k=1;k<=cnt[i];k++){
                    if(dfs(ylink[i][k])){
                        ylink[i][k]=u;
                        return true;
                    }
                }
            }
        }
    }
    return false;
}

bool sove(){
    int flag=1;
    memset(cnt,0,sizeof(cnt));
    for(int i=1;i<=n;i++){
        memset(vis,false,sizeof(vis));
        if(!dfs(i)){flag=0;break;}
    }
    if(flag)return true;
    else return false;
}

int main()
{
    while(~scanf("%d%d",&n,&m),n+m){

        memset(mp,0,sizeof(mp));
        char str[10000];
        for(int i=1;i<=n;i++){
            scanf("%s",str);
            getchar();
            gets(str);
            int len = strlen(str);
            str[len]=' ';
            char ch[5];
            int num=0,flag=0;
            for(int j=0;j<=len;j++){
                if(str[j]==' '){
                    if(flag){
                        ch[num]='\0';
                        int v;sscanf(ch,"%d",&v);
                        mp[i].push_back(v);
                        num=0,flag=0;
                    }
                }else {
                    ch[num++]=str[j];
                    flag=1;
                }
            }
        }
        int l = 1,r=n,ans;
        while(l<=r){
            mid = (l+r)>>1;
            if(sove()){
                ans = mid;
                r=mid-1;
            }else l=mid+1;
        }
        printf("%d\n",ans);
    }
    return 0;
}