#include <bits/stdc++.h>
using namespace std;

struct iofast_t {
    iofast_t() {
        ios::sync_with_stdio(false);
        cin.tie(nullptr);
    }
} iofast;

struct uns_t {} uns;
template <typename Element, typename Head, typename ...Args>
auto vec(Element init, Head arg, Args ...args) {
    if constexpr (sizeof...(Args) == 0) return std::vector(arg, init);
    else return std::vector(arg, vec(init, args...));
}
template <typename Element, typename Head, typename ...Args>
auto vec(uns_t, Head arg, Args ...args) {
    return vec(Element(), arg, args...);
}

template <typename T, typename Compare = less<T>>
T &chmin(T &l, T r, Compare &&f = less<T>()) { return l = min(l, r, f); }
template <typename T, typename Compare = less<T>>
T &chmax(T &l, T r, Compare &&f = less<T>()) { return l = max(l, r, f); }

int main() {
    int n, k; cin >> n >> k;

    auto a = vec<int>(uns, n);
    auto g = vec<int>(uns, n, 0);
    for (int i = 0; i < n; ++i) {
        int m; cin >> a[i] >> m;
        while (m--) {
            int b; cin >> b; --b;
            g[b].push_back(i);
        }
    }

    auto dp = vec<int64_t>(0, n + 1);

    for (int i = n - 1; 0 <= i; --i) {
        dp[i] = dp[i + 1];
        for (auto v : g[i]) {
            chmax(dp[i], dp[v] + (a[v] - a[i]));
        }
    }

    cout << dp[0] << endl;
}