10986

// unsolved
#include <algorithm>
#include <bitset>
#include <cctype>
#include <cmath>
#include <complex>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <deque>
#include <fstream>
#include <iostream>
#include <list>
#include <map>
#include <memory>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <utility>
#include <vector>
#include <iomanip>
using namespace std;
/*** typedef ***/
#define MEMSET_INF 127
#define MEMSET_HALF_INF 63
#define stream istringstream
#define rep(i,n) for(__typeof(n) i=0; i<(n); i++)
#define repl(i,n) for(__typeof(n) i=1; i<=(n); i++)
#define FOR(i,a,b) for(__typeof(b) i=(a); i<=(b); i++)
#define INF (1<<30)
#define PI acos(-1.0)
#define pb push_back
#define ppb pop_back
#define all(x) x.begin(),x.end()
#define mem(x,y) memset(x,y,sizeof(x))
#define eps 1e-9
#define pii pair<int,int>
#define pmp make_pair
#define ft first
#define sd second
#define vi vector<int>
#define vpii vector<pii>
#define si set<int>
#define msi map<string , int >
#define mis map<int , string >
typedef long long i64;
typedef unsigned long long ui64;
/** function **/
#define SDi(x) sf("%d",&x)
#define SDl(x) sf("%lld",&x)
#define SDs(x) sf("%s",x)
#define SD2(x,y) sf("%d%d",&x,&y)
#define SD3(x,y,z) sf("%d%d%d",&x,&y,&z)
#define pf printf
#define sf scanf
#define READ(f) freopen(f, "r", stdin)
#define WRITE(f) freopen(f, "w", stdout)
const i64 INF64 = (i64)1E18;
const i64 INFFF = 1e16;

#define Max 20010

class Compare {
public:
    int operator() ( const pii& p1, const pii& p2 ) {
        return p1.second > p2.second;
    }

};

priority_queue <pii, vector<pii>, Compare> q;
vector <pii> adj[Max];
int dis[Max];

void reset() {
    q = priority_queue <pii, vector<pii>, Compare> ();
    rep(i, Max) {
        dis[i] = INFFF;
        adj[i].clear();
    }
}

int dijkstra(int src, int des) {
    dis[src] = 0;
    q.push(pii(src, dis[src]));
    while(!q.empty()) {
        int u = q.top().first;
        q.pop();
        if(u == des) return dis[des];
        rep(i, (int)adj[u].size()) {

            int v = adj[u][i].first;
            int cost = adj[u][i].second;
            if(dis[v] > dis[u] + cost) {
                dis[v] = dis[u] + cost;
                q.push(pii(v, dis[v]));
            }
        }
    }
    return -1;
}

int main() {
    READ("input.txt");
    int vertex, edge, u, v, cost, src, des, tcase, caseNo = 1;
    SDi(tcase);
    while(tcase--) {
        cin >> vertex >> edge >> src >> des;
        rep(i, edge) {
            cin>> u >> v >> cost;
            adj[u].pb(pii(v, cost));
            adj[v].pb(pii(u, cost));
        }
        int result = dijkstra(src, des);
        cout << "Case #" << caseNo << ": ";
        if(result == -1) cout << "unreachable\n";
        else cout << result << "\n";
        caseNo++;
        reset();
    }
    return 0;
}