#include<iostream>
#include<vector>
#include<queue>
#define ll long long
 
using namespace std;
struct node{
	ll v;
	double w;
};
struct comp{
	bool operator()(const node &a,const node &b) const
	{
		return a.w>b.w;
	}
};
float findMin(vector<pair<ll,double>> adj[],bool visited[],double dist[],ll a,ll b){
	dist[a] = 0;
	priority_queue<node,vector<node>,comp> q;
	q.push({a,0});
    visited[a] = true;
	while(!q.empty()){
		node p = q.top();
        q.pop();
		for(auto x:adj[p.v]){
			if(!visited[x.first]&&dist[x.first]> dist[p.v] + x.second){
				dist[x.first] =  dist[p.v] + x.second;
				q.push({x.first,dist[x.first]});
			}
		}
		visited[p.v] = true;
	}
if(visited[b])
	return dist[b];
else return -1;
}
int main(){
	int t;
	cin >>t;
	while(t--){
		ll n,m,a,b,i,x,y,d,s;
		cin >> n>>m>>a>>b;
		vector<pair<ll,double>> adj[n+1];
		bool visited[n+1];
		double dist[n+1];
		for(i=0;i<=n;i++){
            visited[i] = false;
			dist[i] = 1e18;
		}
		for(i=0;i<m;i++){
			cin >>x>>y>>d>>s;
			adj[x].push_back(make_pair(y,(double)d/s));
			adj[y].push_back(make_pair(x,(double)d/s));
		}
		cout <<findMin(adj,visited,dist,a,b)<<endl;
	}
return 0;
}
 

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