#include<bits/stdc++.h>
using namespace std;
const long long inf = (long long) 1e18 + 10;
const int inf1 = (int) 1e9 + 10;
#define int long long
#define dbl long double
#define endl '\n'
#define sc second
#define fr first
#define mp make_pair
#define pb push_back
#define all(x) x.begin(), x.end()
const int maxn = 5e4+10;
int n, k, gr[maxn];
vector<int> g[maxn];
set<int> stg[maxn];
void solve() {
cin >> n >> k;
int ans = 1;
for(int i = 0; i < n; i++) {
int d; cin >> d;
gr[i] = d;
if(d != 0) ans = 2;
while(d--) {
int x; cin >> x;
stg[i].insert(x);
g[i].pb(x);
}
}
set<pair<int,int>> st;
for(int i = 0; i < n; i++) {
st.insert(mp(gr[i],i));
}
while(st.size()) {
int u = st.begin()->sc;
st.erase(st.begin());
if(gr[u]+1 <= k) {
bool ok = true;
for(auto v1 : stg[u]) {
for(auto v2 : stg[u]) {
if(v1 != v2 && stg[v1].count(v2) == 0) ok = false;
}
}
if(ok) ans = max(ans, gr[u]+1);
}
for(auto v : stg[u]) {
stg[v].erase(u);
st.erase(mp(gr[v],v));
--gr[v];
st.insert(mp(gr[v],v));
}
}
cout << ans << endl;
}
int32_t main() {
ios::sync_with_stdio(false); cin.tie(0);
// freopen("in.in", "r", stdin);
// freopen("out.out", "w", stdout);
int tt = 1;
// cin >> tt;
while(tt--) {
solve();
}
}
