建议加强数据

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll N=2010;
vector<pair<ll,ll> > e[N];
ll n,m,dis[N],ans;
bool st[N];
ll dfs(ll u) {
	if(dis[u]) return dis[u];
	dis[u]=1;
	for(ll i=0; i<e[u].size(); ++i) {
		ll v=e[u][i].first,w=e[u][i].second;
		dis[u]=max(dis[u],dfs(v)+w);
	}
	return dis[u];
}
int main() {
	freopen("level.in","r",stdin);
	freopen("level.out","w",stdout);
	ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	cin>>n>>m;
	for(ll i=1,s,x; i<=m; ++i) {
		cin>>s;
		memset(st,0,sizeof(st));
		ll str=n,end=0;
		while(s--) {
			cin>>x;
			st[x]=1;
			str=min(str,x),end=max(end,x);
		}
		for(ll j=str; j<=end; ++j)
			if(st[j]) e[n+i].push_back({j,1});
			else e[j].push_back({n+i,0});
	}
	for(ll i=1; i<=n; ++i) ans=max(ans,dfs(i));
	cout<<ans;
	return 0;
}