#include <bits/stdc++.h>
using namespace std;
#define fast ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define ll long long
#define ld double
#define llu long long unsigned

# define INF 0x3f3f3f3f

typedef pair<int, int> iPair;

class Graph
{
    int V;

    list< pair<int, int> > *adj;

public:
    Graph(int V);

    void addEdge(int u, int v, int w);

    void shortestPath(int s);
};

Graph::Graph(int V)
{
    this->V = V;
    adj = new list<iPair> [V];
}

void Graph::addEdge(int u, int v, int w)
{
        adj[u].push_back(make_pair(v, w));
        adj[v].push_back(make_pair(u, w));
}

void Graph::shortestPath(int src)
{
    priority_queue< iPair, vector <iPair> , greater<iPair> > pq;

    vector<int> dist(V, INF);

    pq.push(make_pair(0, src));
    dist[src] = 0;

    while (!pq.empty())
    {
        int u = pq.top().second;
        pq.pop();

        list< pair<int, int> >::iterator i;
        for (i = adj[u].begin(); i != adj[u].end(); ++i)
        {

            int v = (*i).first;
            int weight = (*i).second;

            if (dist[v] > max(dist[u] , weight) )
            {
                dist[v] = max(dist[u] , weight);
                pq.push(make_pair(dist[v], v));
            }
        }
    }

    for (int i = 0; i < V; ++i)
    {
        if( dist[i] > 20001 )
            cout<<"Impossible\n";
        else
            printf("%d\n", dist[i]);
    }

}

int main()
{
    fast;
    int t;
    cin>>t;
    int count = 0;
    for( count = 1 ; count <= t ; count++ )
    {
        cout<<"Case "<<count<<": "<<'\n';
        int n , e;
        cin>>n>>e;
        Graph g(n);
        while( e-- )
        {
            int u , v , w;
            cin>>u>>v>>w;
            g.addEdge(u, v, w);
        }
        int x;
        cin>>x;

        g.shortestPath( x );

    }

    return 0;
}