import java.util.*;

public class scorify {
    public static void main (String[] args) {
        Scanner in = new Scanner(System.in);
        int T = in.nextInt();

        while(T-->0) {
            int V = in.nextInt();
            int E = in.nextInt();
            int K = in.nextInt();

            Vector<Pair>[] adjList = new Vector[V];
            for(int i = 0; i < V; ++i) {
                adjList[i] = new Vector<Pair>();
            }

            for(int i = 0; i < E; ++i) {
                int u = in.nextInt();
                int v = in.nextInt();
                int w = in.nextInt();

                adjList[u-1].add(new Pair(v-1, w));
                adjList[v-1].add(new Pair(u-1, w));
            }


            // DIJKSTRA
            int S = in.nextInt() - 1;
            int D = in.nextInt() - 1;

            int[] dist = new int[V];
            Arrays.fill(dist, Integer.MAX_VALUE);
            dist[D] = 0;
            PriorityQueue<State> pq = new PriorityQueue();
            pq.offer(new State(D, 0, 0));
            while(!pq.isEmpty()){
                State st = pq.poll();
                int u = st.u;
                int dd = st.d;
                int str = st.s;
                if(str > K) continue;

                if(dist[u] < dd) continue;
                dist[u] = Math.min(dist[u], dd);

                for(Pair pp: adjList[u]) {
                    pq.offer(new State(pp.f, dd + pp.s, str + 1));
                }
            }

            if(dist[S] == Integer.MAX_VALUE)
                System.out.println(-1);
            else
                System.out.println(dist[S]);
        }
    }
}

class Pair{
    int f, s;

    public Pair(int f, int s) {
        this.f = f;
        this.s = s;
    }
}

class State implements Comparable<State> {
    int u, d, s;

    public State(int u, int d, int s) {
        this.u = u;
        this.d = d;
        this.s = s;
    }

    @Override
    public int compareTo(State st) {
        return this.d - st.d;
    }
}