#include <bits/stdc++.h>
#include <atcoder/lazysegtree>
#define int long long
using namespace std;
using namespace atcoder;
using vec_int = vector<int>;
using vec_ii = vector<vec_int>;
using vec_iii = vector<vec_ii>;
using vec_iiii = vector<vec_iii>;
using P = pair<int,int>;
using T = tuple<int,int,int>;
using ll = long long;
using ld = long double;
#define rep(i, n) for(int i = 0; i < (int)(n); i++)

void cout_line(vector<int> &a){
    for(int i=0;i<a.size();i++){
        if(i<a.size()-1){
            cout<<a.at(i)<<" ";
        }else{
            cout<<a.at(i)<<endl;
        }
    }
}


signed main(){
    ios::sync_with_stdio(false);
    std::cin.tie(nullptr);

    int N, K; cin>>N>>K;
    vec_int A(N), M(N);
    vector<vec_int> B(N);
    vector<vec_int> G(N+1);
    rep(i,N){
        cin>>A.at(i)>>M.at(i);
        rep(j, M.at(i)){
            int num;
            cin>>num;
            B.at(i).push_back(num);
            G.at(num).push_back(i+1);
        }
    }

    vec_int DP(N+1, 0);

    for(int i=1;i<=N;i++){
        DP.at(i) = max(DP.at(i), DP.at(i-1));
        for(int j=0;j<G.at(i).size();j++){
            int next = G.at(i).at(j);
            DP.at(next) = max(DP.at(next), DP.at(i) + A.at(next-1)-A.at(i-1));
        }
    }
    cout<<DP.at(N)<<endl;



    return 0;
}