#include <bits/stdc++.h>

using namespace std;

#define ll long long
#define FOR(i, j, k, in) for (int i=j; i<k; i+=in)
#define RFOR(i, j, k, in) for (int i=j; i>=k; i-=in)
#define REP(i, j) FOR(i, 0, j, 1)
#define RREP(i, j) FOR(i, j, 0, 1)
#define ALL(a) a.begin(), a.end()
#define RALL(a) a.end(), a.begin()
#define F first
#define S second
#define PB push_back
#define MP make_pair
#define pii pair<int, int>
#define MOD 1000000007

void solve() {
    ll n, m, a, b;
    cin >> n;
    vector<vector<ll>> dp;
    map<int, int> tr;
    tr.insert({0, 0});
    REP(i, n) {
        vector<pii> changes;
        cin >> m;
        REP(j, m) {
            cin >> a >> b;
            if (tr.count(a) == 1) {
                changes.PB({0, tr[a] + b});
            }
            changes.PB({a, tr[0] - b});
        }
        for (pii c: changes) {
            if (tr.count(c.F) == 1) {
                tr[c.F] = max(tr[c.F], c.S);
            } else {
                tr[c.F] = c.S;
            }
        }
    }
    cout << tr[0] << endl;
}

signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    ll n=1;
    //  cin >> n;
    REP(i, n) {
        solve();
    }
    return 0;
}