#include <iostream>
#include <vector>
using namespace std;

struct Depreciation {
    int month;
    double rate;
};

int main() {
    while (true) {
        int duration, records;
        double down_payment, loan_amount;
        cin >> duration;
        if (duration < 0) break;
        cin >> down_payment >> loan_amount >> records;

        vector<double> rates(duration + 1);
        for (int i = 0; i < records; ++i) {
            int m;
            double r;
            cin >> m >> r;
            rates[m] = r;
        }
        // Fill in missing months with last known rate
        for (int i = 1; i <= duration; ++i) {
            if (rates[i] == 0) rates[i] = rates[i - 1];
        }

        double car_value = loan_amount + down_payment;
        double owed = loan_amount;
        double monthly_payment = loan_amount / duration;

        car_value *= (1 - rates[0]);
        int month = 0;

        while (owed >= car_value) {
            month++;
            owed -= monthly_payment;
            car_value *= (1 - rates[month]);
        }

        cout << month << " month";
        if (month != 1) cout << "s";
        cout << endl;
    }
    return 0;
}