#include <bits/stdc++.h>
#define int long long
#define mk make_pair
#define PII pair<int,int>
#define FOR(i,j,k) for(int i=(j);i<=(k);++i)
#define ROF(i,j,k) for(int i=(j);i>=(k);--i)
#define FOI(a,b) for(auto a : b)
#define wh while
#define inf 0x3f3f3f3f3f3f3f3f
#define IOS ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define snd second
#define fst first
#define pb push_back
#define CI const int
#define NP namespace
using NP std;
int quickpow(int a,int b)
{
	int ans=1;
	wh(b)
	{
		if(b&1)ans=ans*a;
        a=a*a;
		b>>=1;
	}
	return ans;
}
CI MAXN=1e3+5;
struct node
{
	int x,y,z;
}a[MAXN];
double ans=inf;
int door[MAXN],f[MAXN],n,m;
int find(int x)
{
	if(x==f[x])return x;
	return f[x]=find(f[x]);
}
void merge(int x,int y)
{
	int fx=find(x),fy=find(y);
	if(fx==fy)return;
	f[fy]=fx;
}
vector<pair<int,int>>v;
double getdist(node a,node b)
{
	return sqrt((a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y)+(a.z-b.z)*(a.z-b.z));
}
signed main(void)
{

    freopen("cube.in","r",stdin);
    freopen("cube.out","w",stdout);
    cout<<fixed<<setprecision(4); 
	IOS
	cin>>n>>m;
	FOR(i,1,n)
	{
		cin>>a[i].x>>a[i].y>>a[i].z>>door[i];
	}
	FOR(i,1,m)
	{
		int u,v_;
		cin>>u>>v_;
		v.pb({u,v_});
	}
	vector<int> high;
	FOR(i,1,n)
	{
		high.pb(a[i].z);
	}
	sort(high.begin(),high.end());
	high.erase(unique(high.begin(),high.end()),high.end());
	FOI(hi,high)
	{
		if(hi<a[1].z||hi<a[n].z)continue;
		FOR(i,1,n)f[i]=i;
		vector<bool>ok(n+1);
		FOR(i,1,n)
		{
			if(a[i].z<=hi)ok[i]=1;
		}
		FOI(s,v)
		{
			if(ok[s.fst]&&ok[s.snd])
			{
				merge(s.fst,s.snd);
			}
		}
		vector<int> alldoor(n+1);
		vector<int> po;
		FOR(i,1,n)
		{
			int fi=find(i);
			if(fi==i)po.pb(i);
			alldoor[fi]+=door[i];
		}
		int fs=find(1);
		int fe=find(n);
		if(fs==fe)
		{
			ans=min(ans,0.3*alldoor[fs]);
			continue;
		}
		if(alldoor[fs]<1||alldoor[fe]<1)continue;
		vector<vector<double>>dist(n+1,vector<double>(n+1,inf));
		FOR(i,1,n)
		{
			if(!ok[i])continue;
			FOR(j,1,n)
			{
				if(!ok[j])continue;
				int l=find(i);
				int r=find(j);
				if(l==r)continue;
				if(dist[l][r]>getdist(a[i],a[j]))
				{
					dist[l][r]=getdist(a[i],a[j]);
					dist[r][l]=getdist(a[i],a[j]);
				}
			}
		}
		priority_queue<pair<double,int>,vector<pair<double,int>>,greater<> >  q;
		vector<double> d(n+1,inf);
		vector<double> st(n+1);
		d[fs]=alldoor[fs]*0.3;
		q.push({d[fs],fs});
		wh(q.size())
		{
			pair<double,int> front=q.top();
			double di=front.fst;
			int p=front.snd;
			q.pop();
			if(st[p])continue;
			st[p]=1;
			FOI(s,po)
			{
				if(p!=fs)if(alldoor[s]<1 || alldoor[p]<1)continue; 
				else if(alldoor[s] <1 || alldoor[p]<2)continue;
				if(d[s]>d[p]+(dist[p][s]-0.6)+alldoor[s]*0.3)
				{
//					cout<<p<<" "<<s<<endl;
//					cout<<d[p] <<" "<<dist[p][s]-0.6<<" "<<alldoor[s]*0.3<<endl;
					d[s]=d[p]+(dist[p][s]-0.6)+alldoor[s]*0.3;
					q.push({d[s],s});
					
				}
			}
		}
		ans=min(ans,d[fe]);
	}
	if(ans>=inf/2)cout<<"impossible";
	else cout<<ans;
    return false;
}