#include <iostream>
#include <vector>

using namespace std;

int main (){
    int numOfCities;
    cin >> numOfCities;

    vector<int> profit(10);
    vector<int> lastPrice(10);

    for (int cityPos = 0; cityPos < numOfCities; ++cityPos) {
        int numOfCranes;
        cin >> numOfCranes;
        for (int cranes = 0; cranes < numOfCranes; ++cranes) {
            int typeOfCrane, priceOfCrane;
            cin >> typeOfCrane;
            cin >> priceOfCrane;

            //cerr << "City#" << cityPos << endl;
            //cerr << "Type:" << typeOfCrane << "|Price:"  << priceOfCrane << endl;



            if(cityPos == 0){
                lastPrice[typeOfCrane] = priceOfCrane;
                continue;
            }

            if(lastPrice[typeOfCrane] < priceOfCrane){
                profit[typeOfCrane] += priceOfCrane - lastPrice[typeOfCrane];
            }
            lastPrice[typeOfCrane] = priceOfCrane;
        }
    }
    int maxProfit = 0;

    for (int i = 0; i < 10; ++i) {
        if(profit[i] > maxProfit) maxProfit = profit[i];
    }

    cout << maxProfit << endl;


    return 0;
}