#include <iostream>
#include <unordered_map>
#include <algorithm>

int main() {
    int N;
    std::cin >> N;
    std::unordered_map<int, long long> profit_with_crane;

    long long profit = 0;
    while(N--) {
        int M;
        std::cin >> M;
        std::unordered_map<int, int> cranes;
        while (M--) {
            int id, price;
            std::cin >> id >> price;
            cranes[id] = price;
        }

        for (const auto &crane : cranes) {
            if (profit_with_crane.count(crane.first))
                profit = std::max(profit, profit_with_crane[crane.first] + crane.second);
        }

        for (const auto &crane : cranes) {
            if (!profit_with_crane.count(crane.first))
                profit_with_crane[crane.first] = profit - crane.second;
            else
                profit_with_crane[crane.first] = std::max(profit_with_crane[crane.first], profit - crane.second);
        }
    }

    std::cout << profit << '\n';

    return 0;
}