#include<bits/stdc++.h>
using namespace std;

#define INF     1e7

vector< pair<int,int> >edges[101];
int dis[101],n;

void dijkstra()
{
    int i;
    for(i=1;i<=n;i++)
        dis[i]=INF;
    dis[1]=0;
    priority_queue < pair<int,int> , vector< pair<int,int> > , greater < pair<int,int> > > pq;
    pq.push(make_pair(dis[1],1));
    while(!pq.empty())
    {
        int u = pq.top().second;
        pq.pop();
        for(int i=0;i<edges[u].size();i++)
        {
            int v = edges[u][i].first;
            int w = edges[u][i].second;
            if(dis[v]>dis[u]+w)
            {
                dis[v]=dis[u]+w;
                pq.push(make_pair(dis[v],v));
            }
        }
    }
    return;
}

int main()
{
    int t,i,j,k,l,m,u,v,w;
    scanf("%d",&t);
    for(i=1;i<=t;i++)
    {
        scanf("%d%d",&n,&m);
        for(j=1;j<=n;j++)
            edges[j].clear();
        for(j=0;j<m;j++)
        {
            scanf("%d%d%d",&u,&v,&w);
            edges[u].push_back(make_pair(v,w));
            edges[v].push_back(make_pair(u,w));
        }
        dijkstra();
        if(dis[n]==INF)
            printf("Case %d: Impossible\n",i);
        else
            printf("Case %d: %d\n",i,dis[n]);
    }
}