sending email

import sys
import os
if not os.environ.get("ONLINE_JUDGE"):
    sys.stdin = open('./in.txt', 'r')
    sys.stdout = open('./out.txt', 'w')

inf = sys.maxsize


class Graph():
    def __init__(self, v):
        self.V = v
        self.graph = [[0 for _ in range(v)] for _ in range(v)]

    def mindist(self, dist, dist_set):
        min = sys.maxsize
        min_index = -1
        for v in range(self.V):
            if dist[v] < min and dist_set[v] == False:
                min = dist[v]
                min_index = v

        return min_index

    def dijkstra(self, src, T):
        dist = [sys.maxsize] * self.V
        dist[src] = 0
        dist_set = [False] * self.V

        for node in range(self.V):
            u = self.mindist(dist, dist_set)
            dist_set[u] = True

            for v in range(self.V):
                if self.graph[u][v] > 0 and dist_set[v] == False and dist[v] > dist[u] + self.graph[u][v]:
                    dist[v] = dist[u] + self.graph[u][v]

        return dist[T]


for N in range(int(input())):
    n, m, S, T = map(int, input().split())

    g = Graph(n)
    for _ in range(m):
        u, v, c = map(int, input().split())
        g.graph[u][v] = c
        g.graph[v][u] = c

    ans = g.dijkstra(S, T)
    if ans == inf:
        print(f"Case #{N+1}: unreachable")
    else:
        print(f"Case #{N+1}: {ans}")