#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>

using namespace std;

typedef pair<int, int> Rider;

constexpr int FULL_DISTANCE = 4500 * 3.6;

int ride_time(const Rider& rider, const int distance = FULL_DISTANCE) {
    return static_cast<int>(ceil(static_cast<double>(distance) / rider.first)) + rider.second;
}

int start_pos(const Rider& rider) {
    if (rider.second >= 0) { return 0; }
    return rider.first * -rider.second;
}

int arrival_time(const vector<Rider>& riders, const int distance = FULL_DISTANCE) {
    vector<Rider> early_riders, late_riders;
    for (const auto& rider : riders) {
        if (rider.second >= 0) {
            late_riders.push_back(rider);
        } else {
            // early_riders.push_back(rider);
        }
    }
    double min_time = ride_time(*min_element(
        late_riders.begin(), late_riders.end(),
        [distance](const Rider& a, const Rider& b) {
            return ride_time(a, distance) < ride_time(b, distance);
        }));
    clog << "min_time: " << min_time << endl;
    // for (const auto& rider : early_riders) {
    //     if (-rider.second > min_time) { continue; }
    //     min_time = min(min_time, ride_time(rider, distance));
    // }
    return static_cast<int>(ceil(min_time));
}


int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int rider_count;
    while (cin >> rider_count && rider_count) {
        vector<Rider> riders(rider_count);
        for (int i = 0; i < rider_count; i++) {
            cin >> riders[i].first >> riders[i].second;
            // riders[i].first /= 3.6;
        }
        cout << arrival_time(riders) << endl;
    }

    return 0;
}