#include <bits/stdc++.h>

using namespace std;
using ll = long long;

#define all(x) begin(x), end(x)

struct P {
	int id;
	int pr;
};

int main()
{

	int n;
	cin >> n;
	unordered_map<int, int> cm;
	int ii = 0;
	vector<vector<P>> cs(n);
	for(int i = 0; i < n; ++i) {
		int m;
		cin >> m;
		for(int j = 0; j < m; ++j) {
			int id, p;
			cin >> id >> p;
			if(cm.find(id) == cm.end()) {
				cm[id] = ii;
				++ii;
			}
			cs[i].push_back({cm[id], p});

		}
	}
	ll b = 0;
	vector<ll> sts(ii, -2e9);
	for(int i = 0; i < n; ++i) {
		for(auto& c : cs[i]) {
			b = max(sts[c.id] + c.pr, b);
		}
		for(auto& c : cs[i]) {
			sts[c.id] = max(b - c.pr, sts[c.id]);
		}
	}

	cout << b << '\n';
    return 0;
}