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

typedef long long int ll;
int t, d, n;
vector<int> a, b, p;

bool f(double v) {
    int time = 0, len = 0;
    for(int i = 0; i < p.size(); i++) {
        time += (p[i] - len) / v + 1;
        len += p[i];
        if(time % (a[i] + b[i]) <= a[i]) {
            time += (time % (a[i] + b[i])) - 1;
        }
    }
    time += (d - len) / v + 1;
    if(time <= t)
        return true;
    else return false;
}


int main() {
    //freopen("che.in", "r", stdin);
    //freopen("che.out", "w", stdout);
    cin >> t >> d >> n;
    a.resize(n);
    b.resize(n);
    p.resize(n);
    for(int i = 0; i < n; i++) {
        cin >> a[i] >> b[i] >> p[i];
    }
    double l = 1.0, r = 4;
    for(int i = 0; i < 1000; i++) {
        double m = (r - l) / 2;
        if(f(m)) {
            r = m;
        }
        else l = m;
    }
    cout << l;
    return 0;
}