#include<bits/stdc++.h>
typedef long long ll;
using namespace std;
const int N = 501;
int dp[N][N][2];
vector<int> G[N];
int solve_dp(int u, int v, bool state) {
if (u == v) return dp[u][v][state] = 0;
if (dp[u][v][state] != -1) return dp[u][v][state];
int l = min(u, v), r = max(u, v);
if (state) {
for (auto w : G[r]) {
if (l < w && w < r) {
dp[u][v][1] = max(dp[u][v][1], solve_dp(u, w, 1) + 1);
dp[u][v][1] = max(dp[u][v][1], solve_dp(v, w, 1) + 1);
}
}
} else {
for (auto w : G[r]) {
if (!(l < w && w < r)) {
if (w > v) {
dp[u][v][0] = max(dp[u][v][0], solve_dp(v, w, 1) + 1);
} else {
dp[u][v][0] = max(dp[u][v][0], solve_dp(v, w, 0) + 1);
}
if (w > u) {
dp[u][v][0] = max(dp[u][v][0], solve_dp(u, w, 0) + 1);
} else {
dp[u][v][0] = max(dp[u][v][0], solve_dp(u, w, 1) + 1);
}
}
}
}
return dp[u][v][state];
}
int main()
{
// ifstream cin("input.txt");
// ofstream cout("output.txt");
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int n, k; cin >> n >> k;
set<pair<int, int>> edges;
for (int i = 0; i < n; i++) {
while(true) {
int u; cin >> u;
if (!u) break;
u--;
G[i].push_back(u);
edges.insert({i, u});
}
}
memset(dp, -1, sizeof dp);
int ans = 0;
for (int u = 0; u < n; u++) {
for (int v = 0; v < n; v++) {
for (int state = 0; state < 2; state++) {
dp[u][v][state] = solve_dp(u, v, state);
if (edges.count({u, v})) {
ans = max(ans, dp[u][v][state]);
}
}
}
}
// for (int u = 0; u < n; u++) {
// for (int v = 0; v < n; v++) {
// }
// }
cout << ans << '\n';
}
