1 #include <cstdio>
 2 #include <vector>
 3 #include <queue>
 4 using namespace std;
 5 typedef pair<int, int> ii;
 6 typedef vector<ii> vii;
 7 #define INF 1e9
 8 #define TRvii(c, it) \
 9     for (vii::iterator it = (c).begin(); it != (c).end(); it++)
10
11 int main()
12 {
13 #ifdef LOCAL
14     freopen("in", "r", stdin);
15 #endif
16     int T;
17     scanf("%d", &T);
18     for (int kase = 1; kase <= T; kase++)
19     {
20         int n, m, s, t;
21         scanf("%d%d%d%d", &n, &m, &s, &t);
22         vector<vii> AdjList(n);
23         for (int i = 0; i < m; i++)
24         {
25             int u, v, weight;
26             scanf("%d%d%d", &u, &v, &weight);
27             AdjList[u].push_back(ii(v, weight));
28             AdjList[v].push_back(ii(u, weight));
29         }
30         vector<int> dist(n, INF);
31         dist[s] = 0;
32         priority_queue<ii, vector<ii>, greater<ii> > pq;
33         pq.push(ii(0, s));
34         while (!pq.empty())
35         {
36             ii top = pq.top();
37             pq.pop();
38             int d = top.first, u = top.second;
39             if (d == dist[u])
40                 TRvii(AdjList[u], it)
41                 {
42                     int v = it->first, weight = it->second;
43                     if (dist[u] + weight < dist[v])
44                     {
45                         dist[v] = dist[u] + weight;
46                         pq.push(ii(dist[v], v));
47                     }
48                 }
49         }
50         if (dist[t] != INF)  printf("Case #%d: %d\n", kase, dist[t]);
51         else  printf("Case #%d: unreachable\n", kase);
52     }
53     return 0;
54 }