#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i, n) for (int i = 0; i < int(n); i++)

inline bool chmax(ll &a, ll b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}

int main() {
  int n, k;
  cin >> n >> k;
  vector<ll> a(n);
  vector<int> m(n);
  vector<vector<int>> b(n);
  rep(i, n) {
    cin >> a[i] >> m[i];
    b[i].resize(m[i]);
    rep(j, m[i]) cin >> b[i][j], b[i][j]--;
  }
  vector<ll> dp(n, 0);
  for (int i = 1; i < n; i++) {
    chmax(dp[i], dp[i - 1]);
    for (auto j : b[i]) chmax(dp[i], dp[j] + a[i] - a[j]);
  }
  cout << dp[n - 1] << "\n";
}