#include<iostream>
#include<algorithm>
#include<vector>
#include<queue>
#include<utility>
#define infinity 1000
using namespace std;
typedef pair<int,int > ii;
int main ()
{
    int cases;

    cin>>cases;

    for(int thiscase=1;thiscase<=cases;++thiscase)
    {
        int N,M,S,T;
        cin >> N >> M >> S >> T;
        // node,connect,sever s, sever T
        vector<ii> edge[N];

        for(int m=0;m<M;m++)
        {
            int u,v,w;
            // u=vertex u, v= vertex v
            cin>> u >> v >> w;
            edge[u].push_back(make_pair(v,w));
            edge[v].push_back(make_pair(u,w));
        }
        //Dijkstra’s Algorithm Code
            priority_queue<ii , vector<ii>, greater<ii> > q;

            vector<int> dist;
            dist.assign(N, INT_MAX);  // all vertex  weight  infinity

            dist[S] = 0; //start vertex
            q.push(make_pair(dist[S], S)); //weight frist node=0

            while (!q.empty())
            {
                int current_vertex = q.top().second;

                q.pop();

                for (size_t i = 0; i < edge[current_vertex].size(); i++)
                {
                     int next_vertex = edge[current_vertex][i].first;
                     int w = edge[current_vertex][i].second;

                    if (dist[next_vertex] > dist[current_vertex] + w)
                     {
                        dist[next_vertex] = dist[current_vertex] + w;
                        q.push(make_pair(dist[next_vertex], next_vertex));
                     }
                 }
                 if()
                    cout<<"Case #"<< ;
                else
                    cout<<"Case #"<<"unreachable";

            }
    }







    return 0;
}