#include <bits/stdc++.h>
using namespace std;
const int N = 1e3 + 10;
int B, C, S;
int n, m[N];
struct Task {
    int f, t;
    double e;
};
vector<Task> npc[N];

inline double Calc(int o, double E, double k) {
    vector<double> A(m[o]), B(m[o]);
    vector<double> mx;
    for (int i = 0; i < m[o]; ++i) {
        auto [f, t, e] = npc[o][i];
        A[i] = f * (e - E) * t - C * k * f;
        B[i] = S * k * f;
        mx.push_back(max(A[i], B[i]));
    }
    int cnt = max(m[o] - ::B, 0);
    sort(mx.begin(), mx.end(), greater<double>());
    double ans = 0;
    for(int i = 0; i < cnt; i += 1)
        ans += mx[i];
    for(int i = cnt; i < m[o]; i += 1)
        if(mx[i] > 0)
            ans += mx[i];
    return ans;
}
inline bool Check(double E) {
    double maxL = -1e3, minR = 0;
    for (int i = 1; i <= n; ++i) {
        // npc i
        double L = -1e3, R = 0;
        while((R - L) / max(1., R) > 1e-6) {
            double m1 = L + (R - L) / 3;
            double m2 = R - (R - L) / 3;
            if (Calc(i, E, m1) > Calc(i, E, m2)) L = m1;
            else R = m2;
        }
        double p = L;
        // cout << L << ' ' << R << ' ' << Calc(i, E, p) << endl;
        // exit(0);
        if (Calc(i, E, p) > 0) return 1;
        L = maxL, R = p;
        while((R - L) / max(1., -L) > 1e-6) {
            double mid = (L + R) * 0.5;
            if (Calc(i, E, mid) >= 0) L = mid;
            else R = mid;
        }
        double pl = L;
        L = p, R = minR;
        while ((R - L) / max(1., -L) > 1e-6) {
            double mid = (L + R) * 0.5;
            if (Calc(i, E, mid) >= 0) R = mid;
            else L = mid;
        }
        double pr = L;
        if (pr < maxL || pl > minR) return 1;
        maxL = max(maxL, pl);
        minR = min(minR, pr);
    }
    return 0;
}
int main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    cin >> B >> C >> S;
    cin >> n;
    for (int i = 1; i <= n; ++i) {
        cin >> m[i];
        npc[i].resize(m[i]);
        for (auto &[f, t, e] : npc[i]) cin >> f >> t >> e;
        sort(npc[i].begin(), npc[i].end(), [](Task u, Task v) { return u.f < v.f; });
    }
    double L = 0, R = 1e4;
    while((R - L) / max(1., R) > 1e-7) {
        double mid = (L + R) * 0.5;
        if (Check(mid)) L = mid;
        else R = mid;
    }
    cout << fixed << setprecision(15);
    cout << L << endl;
    return 0;
}