#include<iostream>
#include<cstdio>
#include<vector>
#include<algorithm>
#define N 30000
using namespace std;
const double inf=1e4;
const double INF=1e12;
int read()
{
	char c=0;
	int sum=0;
	while (c<'0'||c>'9') c=getchar();
	while ('0'<=c&&c<='9') sum=sum*10+c-'0',c=getchar();
	return sum;
}
struct reads
{
	int a,b,c;
};
vector<reads>p[N+1];
vector<int>A[N+1];
vector<double>B[N+1];
vector<int>C[N+1];
int n,tb,tc,ts,tp[N+1];
double delta[N+1];
bool cmp(int x,int y)
{
	return delta[x]>delta[y];
}
int get(double x)
{
	int sz;
	long long rst=0;
	double res;
	for (int i=1;i<=n;++i)
	{
		for (int j=0;j<p[i].size();++j) tp[j]=j,delta[j]=max(A[i][j]+B[i][j]*x,(double)(C[i][j]));
		sz=max((int)(p[i].size()-tb),1),nth_element(tp,tp+sz,tp+p[i].size(),cmp),res=0;
		for (int j=0;j<sz;++j) res+=delta[tp[j]];
		if (res>0)
		{
			for (int j=0;j<sz;++j)
			{
				if (A[i][tp[j]]+B[i][tp[j]]*x>C[i][tp[j]]) rst+=A[i][tp[j]];
				else rst+=C[i][tp[j]];
			}
			if (rst>=0) return 0;
			else return 2;
		}
	}
	return 1;
}
bool check(double x)
{
	double l=0,r=INF,mid;
	int d;
	for (int i=1;i<=n;++i)
		for (int j=0;j<p[i].size();++j)
			A[i][j]=p[i][j].a*tc,B[i][j]=1ll*p[i][j].a*p[i][j].c-1ll*p[i][j].a*p[i][j].b*x,C[i][j]=-p[i][j].a*ts;
	for (int i=1;i<=80;++i)
	{
		mid=(l+r)/2,d=get(mid);
		if (d==1) return 0;
		if (!d) l=mid;
		else r=mid;
	}
	return 1;
}
int main()
{
	double l=0,r=inf,mid;
	int t,a,b,c;
	tb=read(),tc=read(),ts=read(),n=read();
	for (int i=1;i<=n;++i)
	{
		t=read();
		for (int j=1;j<=t;++j) a=read(),b=read(),c=b*read(),p[i].push_back((reads){a,b,c});
		A[i].resize(p[i].size()),B[i].resize(p[i].size()),C[i].resize(p[i].size());
	}
	for (int i=1;i<=60;++i)
	{
		mid=(l+r)/2;
		if (check(mid)) l=mid;
		else r=mid;
	}
	printf("%0.12lf\n",(l+r)/2);
	return 0;
}