#include <bits/stdc++.h>
    using namespace std;
    #include <math.h>
    #include <iomanip>
    #include <cstdint>
    #include <string>
    #include <sstream>
    template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
    template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
    #define rep(i,n) for (int i = 0; i < (n); ++i)
    typedef long long ll;
    typedef unsigned long long ull;
    using P=pair<ll,ll>;
    const ll INF=1e9;
    const int mod=1e9+7;

    void solve(){
        int n,k;
        cin>>n>>k;
        vector<ll>dp(n);
        vector<int>a(n);
        ll ans=0;
        rep(i,n){
            int m;
            cin>>a[i]>>m;
            rep(j,m){
                int b;
                cin>>b;
                b--;
                if(i){chmax(dp[i],dp[i-1]);}
                chmax(dp[i],dp[b]+a[i]-a[b]);
            }
        }
        cout<<dp[n-1]<<endl;
    }
 
    int main(){
        ios_base::sync_with_stdio(false);
        cin.tie(NULL);
        
        solve(); 

        return 0;
    }