//Author: Kevin
#include<bits/stdc++.h>
//#pragma GCC optimize("O2")
using namespace std;
#define ll long long
#define ull unsigned ll
#define pb emplace_back
#define mp make_pair
#define ALL(x) (x).begin(),(x).end()
#define rALL(x) (x).rbegin(),(x).rend()
#define srt(x) sort(ALL(x))
#define rev(x) reverse(ALL(x))
#define rsrt(x) sort(rALL(x))
#define sz(x) (int)(x.size())
#define inf 0x3f3f3f3f
#define pii pair<int,int>
#define lb(v,x) (int)(lower_bound(ALL(v),x)-v.begin())
#define ub(v,x) (int)(upper_bound(ALL(v),x)-v.begin())
#define uni(v) v.resize(unique(ALL(v))-v.begin())
#define longer __int128_t
void die(string S){puts(S.c_str());exit(0);}
int b,c,s,n;
vector<array<int,3>> skill[1010];
int gen(int ind,double val,double cost)
{
	vector<array<double,3>> vec;
	for(auto arr:skill[ind])
	{
		double cost1=1.0*(arr[2]-val)*arr[1]+c*cost;
		double cost2=-s*cost;
		if(cost1>cost2)
			vec.pb(array<double,3>{cost1*arr[0],(1.0*(arr[2]-val)*arr[1])*arr[0],c*arr[0]});
		else
			vec.pb(array<double,3>{cost2*arr[0],0,-s*arr[0]});
	}
	rsrt(vec);
	int cnt=0;
	while(sz(vec)&&cnt<b&&vec.back()[0]<0)
	{
		cnt++;
		vec.pop_back();
	}
	double A=0,B=0;
	for(auto arr:vec)
	{
		A+=arr[1];
		B+=arr[2];
	}
	double sum=0;
	for(auto arr:vec)
		sum+=arr[0];
	if(sum<0) return 0;
	if(A>0&&B>0)
		return 1;
	if(A>0) return 2;
	return 4;
}
bool check(double val)
{
	double l=1e-6,r=1e6;
	for(int i=0;i<30;i++)
	{
		double mid=sqrt(l*r);
		int msk=0;
		for(int j=1;j<=n;j++)
		{
			msk|=gen(j,val,mid);
			if(msk&1)
				return true;
			if(msk&2)
				if(msk&4)
					return true;
		}
		if(!msk)
			return false;
		if(msk&2)
			l=mid;
		else
			r=mid;
	}
	return true;
}
int main()
{
	ios_base::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	cin>>b>>c>>s>>n;
	for(int i=1;i<=n;i++)
	{
		int m;
		cin>>m;
		while(m--)
		{
			int f,t,e;
			cin>>f>>t>>e;
			skill[i].pb(array<int,3>{f,t,e});
		}
	}
	double l=0,r=1e5;
	for(int i=0;i<50;i++)
	{
		double mid=(l+r)/2;
		if(check(mid))
			l=mid;
		else
			r=mid;
	}
	printf("%.20lf\n",l);
	return 0;
}